diff --git a/.changeset/large-plants-unite.md b/.changeset/large-plants-unite.md
new file mode 100644
index 00000000000..d0be95ef007
--- /dev/null
+++ b/.changeset/large-plants-unite.md
@@ -0,0 +1,5 @@
+---
+"@primer/react": patch
+---
+
+Bug fix(Avatar): Changed rounded border calculation for the "square" Avatar to better align with existing border styles
diff --git a/packages/react/src/Avatar/Avatar.module.css b/packages/react/src/Avatar/Avatar.module.css
index f20124dedfa..9edbe1cbdce 100644
--- a/packages/react/src/Avatar/Avatar.module.css
+++ b/packages/react/src/Avatar/Avatar.module.css
@@ -13,7 +13,8 @@
   box-shadow: 0 0 0 1px var(--avatar-borderColor);
 
   &:where([data-square]) {
-    border-radius: var(--borderRadius-medium);
+    /* stylelint-disable-next-line primer/borders */
+    border-radius: clamp(4px, calc(var(--avatarSize-regular) - 24px), var(--borderRadius-medium));
   }
 
   &:where([data-responsive]) {