diff --git a/CHANGELOG.md b/CHANGELOG.md
index c59462f7794..e0a7bd31f35 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,7 @@
 
 **Bug fixes**
 
+- Fixed `onClose` invoking with unexpected parameter in `EuiFlyout` ([#4505](https://github.com/elastic/eui/pull/4505))
 - Fixed invalid color entry passed to `EuiBadge` color prop ([#4481](https://github.com/elastic/eui/pull/4481))
 - Fixed `EuiCodeBlock` focus-state if content overflows ([#4463]https://github.com/elastic/eui/pull/4463)
 
diff --git a/src/components/flyout/flyout.tsx b/src/components/flyout/flyout.tsx
index af48f2a10e6..0e942953483 100644
--- a/src/components/flyout/flyout.tsx
+++ b/src/components/flyout/flyout.tsx
@@ -134,7 +134,9 @@ export const EuiFlyout: FunctionComponent<EuiFlyoutProps> = ({
             iconType="cross"
             color="text"
             aria-label={closeButtonAriaLabel || closeAriaLabel}
-            onClick={onClose}
+            onClick={() => {
+              onClose();
+            }}
             data-test-subj="euiFlyoutCloseButton"
           />
         )}