diff --git a/moli-benchmark/wpt-cross-current/failed-cases.txt b/moli-benchmark/wpt-cross-current/failed-cases.txt
index 3067a7828..b796a90d8 100644
--- a/moli-benchmark/wpt-cross-current/failed-cases.txt
+++ b/moli-benchmark/wpt-cross-current/failed-cases.txt
@@ -3087,7 +3087,6 @@ html/semantics/forms/form-submission-target/rel-input-target.html
 html/semantics/forms/textfieldselection/selection.html
 html/semantics/forms/the-input-element/show-picker-cross-origin-iframe.html
 html/semantics/forms/the-select-element/customizable-select/base-appearance-inheritance.html
-html/semantics/forms/the-select-element/customizable-select/option-disabled-optgroup.html
 html/semantics/forms/the-select-element/customizable-select/picker-icon-animation.html
 html/semantics/forms/the-select-element/customizable-select/select-base-appearance-computed-style.html
 html/semantics/forms/the-select-element/customizable-select/select-value-selectedOption.html
diff --git a/moli-benchmark/wpt-cross-current/passed-cases.txt b/moli-benchmark/wpt-cross-current/passed-cases.txt
index a14af4c85..4e3ad6c4d 100644
--- a/moli-benchmark/wpt-cross-current/passed-cases.txt
+++ b/moli-benchmark/wpt-cross-current/passed-cases.txt
@@ -6442,6 +6442,7 @@ html/semantics/forms/the-select-element/common-HTMLOptionsCollection.html
 html/semantics/forms/the-select-element/customizable-select/nested-select-crash.html
 html/semantics/forms/the-select-element/customizable-select/option-color-inheritance.html
 html/semantics/forms/the-select-element/customizable-select/option-disabled-invalid-nesting.html
+html/semantics/forms/the-select-element/customizable-select/option-disabled-optgroup.html
 html/semantics/forms/the-select-element/customizable-select/option-form-ancestor-select.html
 html/semantics/forms/the-select-element/customizable-select/option-list.html
 html/semantics/forms/the-select-element/customizable-select/select-highlight-crash.html
diff --git a/moli-dom/src/forms/mod.rs b/moli-dom/src/forms/mod.rs
index d2f027344..2c26ab096 100644
--- a/moli-dom/src/forms/mod.rs
+++ b/moli-dom/src/forms/mod.rs
@@ -34,7 +34,10 @@ pub use numeric::{
     parse_html_floating_point_prefix, parse_input_numeric_value, progress_element_values,
     step_input_value,
 };
-pub use option::{OptionNearestSelectStep, OptionNearestSelectTraversal};
+pub use option::{
+    OptionDisabledAncestorStep, OptionNearestSelectStep, OptionNearestSelectTraversal,
+    option_disabled_ancestor_step,
+};
 pub use text::{
     normalize_custom_validation_message, normalize_form_submission_newlines,
     parse_non_negative_integer_prefix, parse_non_negative_length_attribute,
diff --git a/moli-dom/src/forms/option.rs b/moli-dom/src/forms/option.rs
index e626d490b..7129c4022 100644
--- a/moli-dom/src/forms/option.rs
+++ b/moli-dom/src/forms/option.rs
@@ -7,6 +7,28 @@ pub enum OptionNearestSelectStep {
     Blocked,
 }
 
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum OptionDisabledAncestorStep {
+    Continue,
+    Disabled(bool),
+}
+
+pub fn option_disabled_ancestor_step(
+    namespace: &str,
+    local_name: &str,
+    has_disabled_attribute: bool,
+) -> OptionDisabledAncestorStep {
+    if namespace != HTML_NAMESPACE {
+        return OptionDisabledAncestorStep::Continue;
+    }
+
+    match local_name {
+        "select" | "hr" | "datalist" | "option" => OptionDisabledAncestorStep::Disabled(false),
+        "optgroup" => OptionDisabledAncestorStep::Disabled(has_disabled_attribute),
+        _ => OptionDisabledAncestorStep::Continue,
+    }
+}
+
 /// State for the HTML "option element nearest ancestor select" algorithm.
 ///
 /// Tree owners perform the actual ancestor walk and feed element names into
@@ -18,6 +40,10 @@ pub struct OptionNearestSelectTraversal {
 }
 
 impl OptionNearestSelectTraversal {
+    pub fn starting_at_optgroup() -> Self {
+        Self { saw_optgroup: true }
+    }
+
     pub fn visit_ancestor(&mut self, namespace: &str, local_name: &str) -> OptionNearestSelectStep {
         if namespace != HTML_NAMESPACE {
             return OptionNearestSelectStep::Continue;
diff --git a/moli-dom/src/native/host/collections/form.rs b/moli-dom/src/native/host/collections/form.rs
index 10feaa45c..48038ecdd 100644
--- a/moli-dom/src/native/host/collections/form.rs
+++ b/moli-dom/src/native/host/collections/form.rs
@@ -166,6 +166,14 @@ impl DomHost {
         self.dom.option_nearest_ancestor_select(handle)
     }
 
+    pub fn optgroup_nearest_ancestor_select(&self, handle: DomHandle) -> Option<DomHandle> {
+        self.dom.optgroup_nearest_ancestor_select(handle)
+    }
+
+    pub fn option_is_disabled(&self, handle: DomHandle) -> bool {
+        self.dom.option_is_disabled(handle)
+    }
+
     pub fn radio_group_members(&self, handle: DomHandle) -> Vec<DomHandle> {
         let Some(element) = self.node(handle).and_then(Node::as_element) else {
             return Vec::new();
@@ -230,26 +238,6 @@ impl DomHost {
             .into_iter()
             .collect()
     }
-
-    fn option_is_disabled(&self, handle: DomHandle) -> bool {
-        let mut current = Some(handle);
-        while let Some(candidate) = current {
-            let Some(element) = self.node(candidate).and_then(Node::as_element) else {
-                current = self.parent_node(candidate);
-                continue;
-            };
-            if matches!(element.local_name(), "option" | "optgroup")
-                && element.has_attribute("disabled")
-            {
-                return true;
-            }
-            if element.is_html_select() {
-                return false;
-            }
-            current = self.parent_node(candidate);
-        }
-        false
-    }
 }
 
 fn select_display_size(select: &Element) -> i32 {
diff --git a/moli-dom/src/native/mod.rs b/moli-dom/src/native/mod.rs
index da89579f2..70ff08e43 100644
--- a/moli-dom/src/native/mod.rs
+++ b/moli-dom/src/native/mod.rs
@@ -1560,11 +1560,13 @@ mod tests {
         assert!(host.append_child(datalist, datalist_option));
 
         let optgroup = host.create_element("optgroup");
+        let optgroup_div = host.create_element("div");
         let optgroup_option = host.create_element("option");
         let nested_optgroup = host.create_element("optgroup");
         let nested_optgroup_option = host.create_element("option");
         assert!(host.append_child(child_select, optgroup));
-        assert!(host.append_child(optgroup, optgroup_option));
+        assert!(host.append_child(optgroup, optgroup_div));
+        assert!(host.append_child(optgroup_div, optgroup_option));
         assert!(host.append_child(optgroup, nested_optgroup));
         assert!(host.append_child(nested_optgroup, nested_optgroup_option));
 
@@ -1587,6 +1589,18 @@ mod tests {
         ] {
             assert_eq!(host.option_nearest_ancestor_select(option), None);
         }
+
+        assert!(host.set_attribute(optgroup, "disabled", ""));
+        assert!(host.option_is_disabled(optgroup_option));
+        for option in [
+            normal_option,
+            nested_option,
+            hr_option,
+            datalist_option,
+            nested_optgroup_option,
+        ] {
+            assert!(!host.option_is_disabled(option));
+        }
     }
 
     #[test]
diff --git a/moli-dom/src/native/queries.rs b/moli-dom/src/native/queries.rs
index 49dc9f0b7..70eb8eec6 100644
--- a/moli-dom/src/native/queries.rs
+++ b/moli-dom/src/native/queries.rs
@@ -2,7 +2,8 @@ use super::NativeDom;
 use super::element::Element;
 use super::node::{NativeNodeId, Node};
 use crate::forms::{
-    OptionNearestSelectStep, OptionNearestSelectTraversal, parse_non_negative_integer_prefix,
+    OptionDisabledAncestorStep, OptionNearestSelectStep, OptionNearestSelectTraversal,
+    option_disabled_ancestor_step, parse_non_negative_integer_prefix,
 };
 
 impl NativeDom {
@@ -73,8 +74,33 @@ impl NativeDom {
             return None;
         }
 
-        let mut traversal = OptionNearestSelectTraversal::default();
-        let mut current = self.parent_node(option_id);
+        self.nearest_ancestor_select(option_id, OptionNearestSelectTraversal::default())
+    }
+
+    pub fn optgroup_nearest_ancestor_select(
+        &self,
+        optgroup_id: NativeNodeId,
+    ) -> Option<NativeNodeId> {
+        if !self
+            .node(optgroup_id)
+            .and_then(Node::as_element)
+            .is_some_and(|element| element.is_html_element("optgroup"))
+        {
+            return None;
+        }
+
+        self.nearest_ancestor_select(
+            optgroup_id,
+            OptionNearestSelectTraversal::starting_at_optgroup(),
+        )
+    }
+
+    fn nearest_ancestor_select(
+        &self,
+        element_id: NativeNodeId,
+        mut traversal: OptionNearestSelectTraversal,
+    ) -> Option<NativeNodeId> {
+        let mut current = self.parent_node(element_id);
         while let Some(parent) = current {
             let Some(element) = self.node(parent).and_then(Node::as_element) else {
                 current = self.parent_node(parent);
@@ -90,6 +116,36 @@ impl NativeDom {
         None
     }
 
+    pub fn option_is_disabled(&self, option_id: NativeNodeId) -> bool {
+        let Some(option) = self.node(option_id).and_then(Node::as_element) else {
+            return false;
+        };
+        if !option.is_html_option() {
+            return false;
+        }
+        if option.has_attribute("disabled") {
+            return true;
+        }
+
+        let mut current = self.parent_node(option_id);
+        while let Some(parent) = current {
+            let Some(element) = self.node(parent).and_then(Node::as_element) else {
+                current = self.parent_node(parent);
+                continue;
+            };
+            match option_disabled_ancestor_step(
+                element.namespace(),
+                element.local_name(),
+                element.has_attribute("disabled"),
+            ) {
+                OptionDisabledAncestorStep::Continue => {}
+                OptionDisabledAncestorStep::Disabled(disabled) => return disabled,
+            }
+            current = self.parent_node(parent);
+        }
+        false
+    }
+
     pub fn select_selected_option_elements(&self, select_id: NativeNodeId) -> Vec<NativeNodeId> {
         let options = self.select_option_elements(select_id);
         let Some(select) = self.node(select_id).and_then(Node::as_element) else {
@@ -208,26 +264,6 @@ impl NativeDom {
         }
         out
     }
-
-    fn option_is_disabled(&self, option_id: NativeNodeId) -> bool {
-        let mut current = Some(option_id);
-        while let Some(candidate) = current {
-            let Some(element) = self.node(candidate).and_then(Node::as_element) else {
-                current = self.parent_node(candidate);
-                continue;
-            };
-            if matches!(element.local_name(), "option" | "optgroup")
-                && element.has_attribute("disabled")
-            {
-                return true;
-            }
-            if element.is_html_select() {
-                return false;
-            }
-            current = self.parent_node(candidate);
-        }
-        false
-    }
 }
 
 fn select_display_size(select: &Element) -> i32 {
diff --git a/moli-renderer-v8/src/context_bootstrap/form_data_runtime/serialize.rs b/moli-renderer-v8/src/context_bootstrap/form_data_runtime/serialize.rs
index 5cd4637c9..89028c5f6 100644
--- a/moli-renderer-v8/src/context_bootstrap/form_data_runtime/serialize.rs
+++ b/moli-renderer-v8/src/context_bootstrap/form_data_runtime/serialize.rs
@@ -1,7 +1,10 @@
 use super::storage::{form_data_entries, form_data_is_object, push_form_data_entry};
 use super::*;
 use crate::custom_elements::is_form_associated_custom_element_handle;
-use crate::dom::{forms::InputType, native::Node};
+use crate::dom::{
+    forms::{InputType, OptionDisabledAncestorStep, option_disabled_ancestor_step},
+    native::Node,
+};
 use crate::native_bridge::{
     element::{
         element_attribute_for_object, element_internals_form_value_for_target,
@@ -504,18 +507,21 @@ fn control_has_datalist_ancestor<'s>(
 }
 
 fn option_is_disabled(scope: &mut v8::PinScope<'_, '_>, option: v8::Local<'_, v8::Object>) -> bool {
-    let mut current = Some(option);
+    if object_bool_property(scope, option, "disabled").unwrap_or(false) {
+        return true;
+    }
+
+    let mut current = object_property_as_object(scope, option, "parentElement");
     while let Some(element) = current {
-        let tag = object_string_property_defined(scope, element, "tagName")
-            .map(|tag| tag.to_ascii_lowercase())
-            .unwrap_or_default();
-        if matches!(tag.as_str(), "option" | "optgroup")
-            && object_bool_property(scope, element, "disabled").unwrap_or(false)
-        {
-            return true;
-        }
-        if tag == "select" {
-            return false;
+        let namespace =
+            object_string_property_defined(scope, element, "namespaceURI").unwrap_or_default();
+        let local_name =
+            object_string_property_defined(scope, element, "localName").unwrap_or_default();
+        let has_disabled_attribute =
+            object_bool_property(scope, element, "disabled").unwrap_or(false);
+        match option_disabled_ancestor_step(&namespace, &local_name, has_disabled_attribute) {
+            OptionDisabledAncestorStep::Continue => {}
+            OptionDisabledAncestorStep::Disabled(disabled) => return disabled,
         }
         current = object_property_as_object(scope, element, "parentElement");
     }
diff --git a/moli-renderer-v8/src/native_bridge/element/forms/owner.rs b/moli-renderer-v8/src/native_bridge/element/forms/owner.rs
index 2a5870653..3127f84bd 100644
--- a/moli-renderer-v8/src/native_bridge/element/forms/owner.rs
+++ b/moli-renderer-v8/src/native_bridge/element/forms/owner.rs
@@ -125,7 +125,7 @@ pub(crate) fn form_control_is_effectively_disabled(
     {
         return true;
     }
-    if option_is_disabled_by_optgroup(runtime, handle) {
+    if runtime.dom_host().option_is_disabled(handle) {
         return true;
     }
 
@@ -161,33 +161,6 @@ fn disabled_attribute_applies_to_control(
             ))
 }
 
-fn option_is_disabled_by_optgroup(runtime: &JsContextHost, handle: DomHandle) -> bool {
-    if !runtime
-        .dom_host()
-        .node(handle)
-        .and_then(Node::as_element)
-        .is_some_and(|element| element.is_html_element("option"))
-    {
-        return false;
-    }
-
-    let mut current = runtime.dom_host().parent_node(handle);
-    while let Some(parent) = current {
-        let Some(parent_element) = runtime.dom_host().node(parent).and_then(Node::as_element)
-        else {
-            current = runtime.dom_host().parent_node(parent);
-            continue;
-        };
-        match parent_element.local_name() {
-            "optgroup" => return parent_element.has_attribute("disabled"),
-            "select" | "hr" | "datalist" | "option" => return false,
-            _ => {}
-        }
-        current = runtime.dom_host().parent_node(parent);
-    }
-    false
-}
-
 fn control_is_in_first_legend(
     runtime: &JsContextHost,
     control: DomHandle,
diff --git a/moli-renderer-v8/src/script_vm/inspector/input_state.rs b/moli-renderer-v8/src/script_vm/inspector/input_state.rs
index 9f16232bd..a4474ccf1 100644
--- a/moli-renderer-v8/src/script_vm/inspector/input_state.rs
+++ b/moli-renderer-v8/src/script_vm/inspector/input_state.rs
@@ -150,28 +150,5 @@ pub(in crate::script_vm) fn current_selection_state(
 }
 
 pub(in crate::script_vm) fn option_is_disabled(runtime: &JsContextHost, handle: DomHandle) -> bool {
-    if runtime
-        .dom_host()
-        .node(handle)
-        .and_then(Node::as_element)
-        .is_some_and(|element| element.has_attribute("disabled"))
-    {
-        return true;
-    }
-
-    let mut current = runtime.dom_host().parent_node(handle);
-    while let Some(parent) = current {
-        let Some(parent_element) = runtime.dom_host().node(parent).and_then(Node::as_element)
-        else {
-            current = runtime.dom_host().parent_node(parent);
-            continue;
-        };
-        match parent_element.local_name() {
-            "optgroup" => return parent_element.has_attribute("disabled"),
-            "select" | "hr" | "datalist" | "option" => return false,
-            _ => {}
-        }
-        current = runtime.dom_host().parent_node(parent);
-    }
-    false
+    runtime.dom_host().option_is_disabled(handle)
 }
diff --git a/moli-renderer-v8/src/script_vm/tests/dom_xhr/style_invalidation.rs b/moli-renderer-v8/src/script_vm/tests/dom_xhr/style_invalidation.rs
index 584c7fe70..b6ff8a298 100644
--- a/moli-renderer-v8/src/script_vm/tests/dom_xhr/style_invalidation.rs
+++ b/moli-renderer-v8/src/script_vm/tests/dom_xhr/style_invalidation.rs
@@ -267,6 +267,42 @@ fn has_pseudo_class_invalidation_updates_derived_form_states() {
     );
 }
 
+#[test]
+fn optgroup_disabled_invalidation_updates_nested_option_computed_style() {
+    let mut vm = new_storage_test_vm("https://nested-option-disabled-style.test/");
+
+    let result = vm
+        .eval(
+            r#"
+(() => {
+  const root = document.documentElement || document.appendChild(document.createElement('html'));
+  const head = document.head || root.appendChild(document.createElement('head'));
+  const body = document.body || root.appendChild(document.createElement('body'));
+  const style = document.createElement('style');
+  style.textContent = 'option { color: black; } option:disabled { color: gray; }';
+  head.append(style);
+
+  const select = document.createElement('select');
+  const optgroup = document.createElement('optgroup');
+  const div = document.createElement('div');
+  const option = document.createElement('option');
+  div.append(option);
+  optgroup.append(div);
+  select.append(optgroup);
+  body.append(select);
+
+  const computed = getComputedStyle(option);
+  const before = computed.color;
+  optgroup.disabled = true;
+  return [before, computed.color, option.matches(':disabled')].join('|');
+})()
+"#,
+        )
+        .expect("nested option disabled style should evaluate");
+
+    assert_eq!(result, "rgb(0, 0, 0)|rgb(128, 128, 128)|true");
+}
+
 #[test]
 fn focus_selector_invalidation_preserves_unrelated_cache_entries() {
     let mut vm = new_storage_test_vm("https://focus-style-cache-targeted.test/");
diff --git a/moli-selector/src/lib.rs b/moli-selector/src/lib.rs
index d74cb1003..ca3784e51 100644
--- a/moli-selector/src/lib.rs
+++ b/moli-selector/src/lib.rs
@@ -1931,6 +1931,70 @@ mod tests {
         assert!(!engine.matches_host(&host, option, ":disabled").unwrap());
     }
 
+    #[test]
+    fn dom_api_selectors_option_disabledness_respects_association_boundaries() {
+        let url = url::Url::parse("https://example.test/").unwrap();
+        let mut host = DomHost::from_dom(NativeDom::new_html(url));
+        host.reset_html_document_shell();
+        let body = host.document_body_handle().unwrap();
+        let engine = QueryEngine;
+
+        let select = host.create_element("select");
+        let optgroup = host.create_element("optgroup");
+        let div = host.create_element("div");
+        let option = host.create_element("option");
+        assert!(host.append_child(body, select));
+        assert!(host.append_child(select, optgroup));
+        assert!(host.append_child(optgroup, div));
+        assert!(host.append_child(div, option));
+        assert!(host.set_attribute(optgroup, "disabled", ""));
+        assert!(engine.matches_host(&host, option, ":disabled").unwrap());
+
+        let disabled_select = host.create_element("select");
+        let valid_optgroup = host.create_element("optgroup");
+        let valid_option = host.create_element("option");
+        let nested_optgroup = host.create_element("optgroup");
+        let nested_optgroup_option = host.create_element("option");
+        let parent_option = host.create_element("option");
+        let nested_option = host.create_element("option");
+        let hr = host.create_element("hr");
+        let hr_option = host.create_element("option");
+        let datalist = host.create_element("datalist");
+        let datalist_option = host.create_element("option");
+        assert!(host.set_attribute(disabled_select, "disabled", ""));
+        assert!(host.append_child(body, disabled_select));
+        assert!(host.append_child(disabled_select, valid_optgroup));
+        assert!(host.append_child(valid_optgroup, valid_option));
+        assert!(host.append_child(valid_optgroup, nested_optgroup));
+        assert!(host.append_child(nested_optgroup, nested_optgroup_option));
+        assert!(host.append_child(disabled_select, parent_option));
+        assert!(host.append_child(parent_option, nested_option));
+        assert!(host.append_child(disabled_select, hr));
+        assert!(host.append_child(hr, hr_option));
+        assert!(host.append_child(disabled_select, datalist));
+        assert!(host.append_child(datalist, datalist_option));
+
+        assert!(
+            engine
+                .matches_host(&host, valid_optgroup, ":disabled")
+                .unwrap()
+        );
+        assert!(
+            engine
+                .matches_host(&host, valid_option, ":disabled")
+                .unwrap()
+        );
+        for handle in [
+            nested_optgroup,
+            nested_optgroup_option,
+            nested_option,
+            hr_option,
+            datalist_option,
+        ] {
+            assert!(!engine.matches_host(&host, handle, ":disabled").unwrap());
+        }
+    }
+
     #[test]
     fn dom_api_selectors_disabled_fieldset_disables_option_descendants() {
         let url = url::Url::parse("https://example.test/").unwrap();
diff --git a/moli-selector/src/stylo/query/pseudo.rs b/moli-selector/src/stylo/query/pseudo.rs
index 8581b69f7..dba3cd832 100644
--- a/moli-selector/src/stylo/query/pseudo.rs
+++ b/moli-selector/src/stylo/query/pseudo.rs
@@ -239,27 +239,17 @@ impl<'a> QueryElement<'a> {
         if self.element().has_attribute("disabled") {
             return true;
         }
-        if self.element().local_name() == "option"
-            && self.parent_element().is_some_and(|(_, parent)| {
-                parent.local_name() == "optgroup" && parent.has_attribute("disabled")
-            })
-        {
+        if self.element().local_name() == "option" && self.host.option_is_disabled(self.handle) {
             return true;
         }
         if matches!(self.element().local_name(), "option" | "optgroup")
-            && self.disabled_select_ancestor().is_some()
+            && self.disabled_associated_select().is_some()
         {
             return true;
         }
         self.disabled_fieldset_ancestor().is_some()
     }
 
-    pub(super) fn parent_element(self) -> Option<(NodeId, &'a Element)> {
-        let parent = self.node().parent_node()?;
-        let element = self.host.node(parent)?.as_element()?;
-        Some((parent, element))
-    }
-
     pub(super) fn disabled_fieldset_ancestor(self) -> Option<NodeId> {
         let mut current = self.node().parent_node();
         while let Some(parent) = current {
@@ -275,22 +265,17 @@ impl<'a> QueryElement<'a> {
         None
     }
 
-    pub(super) fn disabled_select_ancestor(self) -> Option<NodeId> {
-        let mut current = self.node().parent_node();
-        while let Some(parent) = current {
-            let Some(element) = self.host.node(parent).and_then(Node::as_element) else {
-                current = self.host.node(parent).and_then(Node::parent_node);
-                continue;
-            };
-            match element.local_name() {
-                "select" if element.has_attribute("disabled") => return Some(parent),
-                "select" | "option" => return None,
-                "optgroup" if self.element().local_name() == "optgroup" => return None,
-                _ => {}
-            }
-            current = self.host.node(parent).and_then(Node::parent_node);
-        }
-        None
+    pub(super) fn disabled_associated_select(self) -> Option<NodeId> {
+        let select = match self.element().local_name() {
+            "option" => self.host.option_nearest_ancestor_select(self.handle),
+            "optgroup" => self.host.optgroup_nearest_ancestor_select(self.handle),
+            _ => None,
+        }?;
+        self.host
+            .node(select)
+            .and_then(Node::as_element)
+            .is_some_and(|element| element.has_attribute("disabled"))
+            .then_some(select)
     }
 
     pub(super) fn is_inside_first_legend_child(self, fieldset: NodeId) -> bool {