diff --git a/packages/eui/changelogs/upcoming/9267.md b/packages/eui/changelogs/upcoming/9267.md
new file mode 100644
index 00000000000..5fda8cf9827
--- /dev/null
+++ b/packages/eui/changelogs/upcoming/9267.md
@@ -0,0 +1,4 @@
+**Bug fixes**
+
+- Fixed flyout overlay masks not being visible for `EuiDataGrid`'s fullscreen mode by reducing the `z-index` of the fullscreen mode overlay
+
diff --git a/packages/eui/src/components/datagrid/controls/fullscreen_selector.styles.ts b/packages/eui/src/components/datagrid/controls/fullscreen_selector.styles.ts
index c5c00246190..7e4b47db4e7 100644
--- a/packages/eui/src/components/datagrid/controls/fullscreen_selector.styles.ts
+++ b/packages/eui/src/components/datagrid/controls/fullscreen_selector.styles.ts
@@ -14,7 +14,7 @@ import { logicalCSS } from '../../../global_styling';
 export const euiDataGridFullScreenStyles = (euiThemeContext: UseEuiTheme) => {
   const { euiTheme } = euiThemeContext;
 
-  const fullScreenZIndex = Number(euiTheme.levels.header) - 1;
+  const fullScreenZIndex = Number(euiTheme.levels.header) - 2;
 
   return {
     'euiDataGrid--fullScreen': css`