diff --git a/.changeset/perf-basestyles-has-selector.md b/.changeset/perf-basestyles-has-selector.md
new file mode 100644
index 00000000000..f16c623c300
--- /dev/null
+++ b/.changeset/perf-basestyles-has-selector.md
@@ -0,0 +1,8 @@
+---
+'@primer/react': patch
+---
+
+perf(BaseStyles): Remove expensive :has([data-color-mode]) selectors
+
+Remove `:has([data-color-mode])` selectors that scanned the entire DOM on every style recalculation.
+Input color-scheme is already handled by global selectors in the codebase.
diff --git a/packages/react/src/BaseStyles.module.css b/packages/react/src/BaseStyles.module.css
index 76259ac05dd..3e6352c92e6 100644
--- a/packages/react/src/BaseStyles.module.css
+++ b/packages/react/src/BaseStyles.module.css
@@ -60,19 +60,12 @@ details-dialog:focus:not(:focus-visible):not(:global(.focus-visible)) {
   /* stylelint-disable-next-line primer/colors */
   color: var(--BaseStyles-fgColor, var(--fgColor-default));
 
-  /* Global styles for light mode */
-  &:has([data-color-mode='light']) {
-    input & {
-      color-scheme: light;
-    }
-  }
-
-  /* Global styles for dark mode */
-  &:has([data-color-mode='dark']) {
-    input & {
-      color-scheme: dark;
-    }
-  }
+  /*
+   * PERFORMANCE: Removed :has([data-color-mode]) selectors that scanned entire DOM.
+   * Input color-scheme is already handled by global selectors above:
+   *   [data-color-mode='light'] input { color-scheme: light; }
+   *   [data-color-mode='dark'] input { color-scheme: dark; }
+   */
 
   /* Low-specificity default link styling */
   :where(a:not([class*='prc-']):not([class*='PRC-']):not([class*='Primer_Brand__'])) {