diff --git a/.changeset/underline-nav-reduced-motion.md b/.changeset/underline-nav-reduced-motion.md
new file mode 100644
index 00000000000..86b0309ce0c
--- /dev/null
+++ b/.changeset/underline-nav-reduced-motion.md
@@ -0,0 +1,5 @@
+---
+'@primer/react': patch
+---
+
+UnderlineNav and TabNav: skip the loading-counter pulse when prefers-reduced-motion is reduce.
diff --git a/packages/react/src/internal/components/UnderlineTabbedInterface.module.css b/packages/react/src/internal/components/UnderlineTabbedInterface.module.css
index 04f1df2ccc0..4129391431a 100644
--- a/packages/react/src/internal/components/UnderlineTabbedInterface.module.css
+++ b/packages/react/src/internal/components/UnderlineTabbedInterface.module.css
@@ -167,7 +167,10 @@
   border-color: var(--borderColor-default);
   /* stylelint-disable-next-line primer/borders */
   border-radius: 20px;
-  animation: loadingCounterKeyFrames 1.2s ease-in-out infinite alternate;
+
+  @media (prefers-reduced-motion: no-preference) {
+    animation: loadingCounterKeyFrames 1.2s ease-in-out infinite alternate;
+  }
 }
 
 @keyframes loadingCounterKeyFrames {