diff --git a/.changeset/perf-segmentedcontrol-has-selector.md b/.changeset/perf-segmentedcontrol-has-selector.md
new file mode 100644
index 00000000000..82036c5a6f1
--- /dev/null
+++ b/.changeset/perf-segmentedcontrol-has-selector.md
@@ -0,0 +1,5 @@
+---
+'@primer/react': patch
+---
+
+perf(SegmentedControl): Scope :has(:focus-visible) to direct child for O(1) lookup
diff --git a/packages/react/src/SegmentedControl/SegmentedControl.module.css b/packages/react/src/SegmentedControl/SegmentedControl.module.css
index 22b80ae8f33..0d936ae4637 100644
--- a/packages/react/src/SegmentedControl/SegmentedControl.module.css
+++ b/packages/react/src/SegmentedControl/SegmentedControl.module.css
@@ -187,7 +187,8 @@
     }
   }
 
-  &:focus-within:has(:focus-visible) {
+  /* PERFORMANCE: Button is direct child of Item, scope with > for O(1) lookup */
+  &:focus-within:has(> :focus-visible) {
     background-color: transparent;
   }