diff --git a/change/@fluentui-react-combobox-c627d0c3-82f4-4593-8a10-546a41227e16.json b/change/@fluentui-react-combobox-c627d0c3-82f4-4593-8a10-546a41227e16.json
new file mode 100644
index 00000000000000..9bf44465fc0868
--- /dev/null
+++ b/change/@fluentui-react-combobox-c627d0c3-82f4-4593-8a10-546a41227e16.json
@@ -0,0 +1,7 @@
+{
+  "type": "patch",
+  "comment": "fix: popup now defines fallbackPositions to use when it doesn't fit the screen",
+  "packageName": "@fluentui/react-combobox",
+  "email": "sarah.higley@microsoft.com",
+  "dependentChangeType": "patch"
+}
diff --git a/packages/react-components/react-combobox/src/utils/useComboboxPopup.ts b/packages/react-components/react-combobox/src/utils/useComboboxPopup.ts
index b011dada2ce6e4..fe85bf972fefda 100644
--- a/packages/react-components/react-combobox/src/utils/useComboboxPopup.ts
+++ b/packages/react-components/react-combobox/src/utils/useComboboxPopup.ts
@@ -1,4 +1,4 @@
-import { resolvePositioningShorthand, usePositioning } from '@fluentui/react-positioning';
+import { PositioningShorthandValue, resolvePositioningShorthand, usePositioning } from '@fluentui/react-positioning';
 import { ExtractSlotProps, Slot, useMergedRefs } from '@fluentui/react-utilities';
 import type { ComboboxBaseProps } from './ComboboxBase.types';
 import { Listbox } from '../components/Listbox/Listbox';
@@ -24,11 +24,15 @@ export function useComboboxPopup(
 ] {
   const { positioning } = props;
 
+  // Set a default set of fallback positions to try if the dropdown does not fit on screen
+  const fallbackPositions: PositioningShorthandValue[] = ['above', 'after', 'after-top', 'before', 'before-top'];
+
   // popper options
   const popperOptions = {
     position: 'below' as const,
     align: 'start' as const,
     offset: { crossAxis: 0, mainAxis: 2 },
+    fallbackPositions,
     ...resolvePositioningShorthand(positioning),
   };