diff --git a/CHANGELOG.md b/CHANGELOG.md
index eaafa696ed4..8d846cb480b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,10 +1,11 @@
 ## [`master`](https://github.com/elastic/eui/tree/master)
 
-**Note: this release is a backport containing changes originally made in `9.0.0`**
+**Note: this release is a backport containing changes originally made in `9.0.0` and `9.1.0`**
 
 **Bug fixes**
 
 - Fixed keyboard navigation and UI of `EuiComboBox` items in single selection mode ([#1619](https://github.com/elastic/eui/pull/1619))
+- Fixed `EuiComboBox` `activeOptonIndex` error with empty search results ([#1695](https://github.com/elastic/eui/pull/1695))
 
 ## [`6.10.4`](https://github.com/elastic/eui/tree/v6.10.4)
 
diff --git a/src/components/combo_box/__snapshots__/combo_box.test.js.snap b/src/components/combo_box/__snapshots__/combo_box.test.js.snap
index 40176609338..54b0198f286 100644
--- a/src/components/combo_box/__snapshots__/combo_box.test.js.snap
+++ b/src/components/combo_box/__snapshots__/combo_box.test.js.snap
@@ -451,6 +451,7 @@ exports[`props singleSelection selects existing option when opened 1`] = `
   />
   <EuiPortal>
     <EuiComboBoxOptionsList
+      activeOptionIndex={-1}
       areAllOptionsSelected={false}
       data-test-subj=""
       fullWidth={false}
@@ -532,6 +533,7 @@ exports[`props singleSelection selects existing option when opened 1`] = `
       position="bottom"
       rootId={[Function]}
       rowHeight={27}
+      scrollToIndex={-1}
       searchValue=""
       selectedOptions={
         Array [
diff --git a/src/components/combo_box/combo_box.js b/src/components/combo_box/combo_box.js
index 803feacbe2e..0ea962c32f9 100644
--- a/src/components/combo_box/combo_box.js
+++ b/src/components/combo_box/combo_box.js
@@ -73,7 +73,7 @@ export class EuiComboBox extends Component {
       searchValue: initialSearchValue,
       isListOpen: false,
       listPosition: 'bottom',
-      activeOptionIndex: undefined,
+      activeOptionIndex: -1,
       hasFocus: false,
     };
 
@@ -154,7 +154,7 @@ export class EuiComboBox extends Component {
     this.setState(({ activeOptionIndex, matchingOptions }) => {
       let nextActiveOptionIndex;
 
-      if (activeOptionIndex == null) {
+      if (activeOptionIndex < 0) {
         // If this is the beginning of the user's keyboard navigation of the menu, then we'll focus
         // either the first or last item.
         nextActiveOptionIndex = amount < 0 ? matchingOptions.length - 1 : 0;
@@ -186,12 +186,12 @@ export class EuiComboBox extends Component {
   };
 
   hasActiveOption = () => {
-    return this.state.activeOptionIndex != null && this.state.activeOptionIndex < this.state.matchingOptions.length;
+    return this.state.activeOptionIndex > -1 && this.state.activeOptionIndex < this.state.matchingOptions.length;
   };
 
   clearActiveOption = () => {
     this.setState({
-      activeOptionIndex: undefined,
+      activeOptionIndex: -1,
     });
   };
 
@@ -498,7 +498,7 @@ export class EuiComboBox extends Component {
     const stateUpdate = { matchingOptions };
 
     if (activeOptionIndex >= matchingOptions.length) {
-      stateUpdate.activeOptionIndex = undefined;
+      stateUpdate.activeOptionIndex = -1;
     }
 
     return stateUpdate;