diff --git a/.changeset/strong-lemons-rescue.md b/.changeset/strong-lemons-rescue.md
new file mode 100644
index 00000000000..dd5464f408f
--- /dev/null
+++ b/.changeset/strong-lemons-rescue.md
@@ -0,0 +1,5 @@
+---
+"@primer/react": patch
+---
+
+SubNav: Update selected styles to only apply to `data-selected='true'`
diff --git a/packages/react/src/SubNav/SubNav.module.css b/packages/react/src/SubNav/SubNav.module.css
index bb6a4c52c81..bac390dcd4b 100644
--- a/packages/react/src/SubNav/SubNav.module.css
+++ b/packages/react/src/SubNav/SubNav.module.css
@@ -60,7 +60,7 @@
     transition: background-color 0.2s ease;
   }
 
-  &:is([data-selected]) {
+  &:is([data-selected='true']) {
     color: var(--fgColor-onEmphasis);
     background-color: var(--bgColor-accent-emphasis);
     /* stylelint-disable-next-line primer/colors */