diff --git a/eslint.config.mjs b/eslint.config.mjs
index 7eb8a062747a58..26a0dc8dda47a3 100644
--- a/eslint.config.mjs
+++ b/eslint.config.mjs
@@ -592,7 +592,7 @@ export default typescript.config([
       'unicorn/prefer-array-find': 'off', // TODO(ryan953): Fix violations and enable this rule
       'unicorn/prefer-array-flat-map': 'error',
       'unicorn/prefer-array-flat': 'off', // TODO(ryan953): Fix violations and enable this rule
-      'unicorn/prefer-array-index-of': 'off', // TODO(ryan953): Fix violations and enable this rule
+      'unicorn/prefer-array-index-of': 'error',
       'unicorn/prefer-array-some': 'off', // TODO(ryan953): Fix violations and enable this rule
       'unicorn/prefer-date-now': 'error',
       'unicorn/prefer-default-parameters': 'warn', // TODO(ryan953): Fix violations and enable this rule
diff --git a/static/app/components/deprecatedSmartSearchBar/index.tsx b/static/app/components/deprecatedSmartSearchBar/index.tsx
index 24ba6a17b5030e..53e8ca95270a61 100644
--- a/static/app/components/deprecatedSmartSearchBar/index.tsx
+++ b/static/app/components/deprecatedSmartSearchBar/index.tsx
@@ -658,7 +658,8 @@ class DeprecatedSmartSearchBar extends Component<DefaultProps & Props, State> {
 
       let offset = filterTokens[0]!.location.end.offset;
       if (token) {
-        const tokenIndex = filterTokens.findIndex(tok => tok === token);
+        // @ts-expect-error: Mismatched types
+        const tokenIndex = filterTokens.indexOf(token);
         if (tokenIndex !== -1 && tokenIndex + 1 < filterTokens.length) {
           offset = filterTokens[tokenIndex + 1]!.location.end.offset;
         }
@@ -677,7 +678,8 @@ class DeprecatedSmartSearchBar extends Component<DefaultProps & Props, State> {
     const hasExecCommand = typeof document.execCommand === 'function';
 
     if (token && filterTokens.length > 0) {
-      const index = filterTokens.findIndex(tok => tok === token) ?? -1;
+      // @ts-expect-error: Mismatched types
+      const index = filterTokens.indexOf(token) ?? -1;
       const newQuery =
         // We trim to remove any remaining spaces
         query.slice(0, token.location.start.offset).trim() +
diff --git a/static/app/components/replays/useJumpButtons.tsx b/static/app/components/replays/useJumpButtons.tsx
index 4273d72fc52b61..312afa88fd881f 100644
--- a/static/app/components/replays/useJumpButtons.tsx
+++ b/static/app/components/replays/useJumpButtons.tsx
@@ -28,7 +28,10 @@ export default function useJumpButtons({
       targetOffsetMs: currentTime,
       allowExact: true,
     });
-    const index = frames.findIndex(spanFrame => frame === spanFrame);
+    if (!frame) {
+      return frames.length - 1;
+    }
+    const index = frames.indexOf(frame);
     // index is -1 at end of replay, so use last index
     return index === -1 ? frames.length - 1 : index;
   }, [currentTime, frames]);
diff --git a/static/app/stores/selectedGroupStore.tsx b/static/app/stores/selectedGroupStore.tsx
index 33d0c4aeece62f..235876e2943e33 100644
--- a/static/app/stores/selectedGroupStore.tsx
+++ b/static/app/stores/selectedGroupStore.tsx
@@ -139,8 +139,8 @@ const storeConfig: SelectedGroupStoreDefinition = {
     }
 
     const ids = GroupStore.getAllItemIds();
-    const lastIdx = ids.findIndex(id => id === this.state.lastSelected);
-    const currentIdx = ids.findIndex(id => id === itemId);
+    const lastIdx = ids.indexOf(this.state.lastSelected);
+    const currentIdx = ids.indexOf(itemId);
 
     if (lastIdx === -1 || currentIdx === -1) {
       return;
diff --git a/static/app/views/dashboards/widgetBuilder/buildSteps/groupByStep/groupBySelector.tsx b/static/app/views/dashboards/widgetBuilder/buildSteps/groupByStep/groupBySelector.tsx
index 42e5434baebc84..68cfb32173df6a 100644
--- a/static/app/views/dashboards/widgetBuilder/buildSteps/groupByStep/groupBySelector.tsx
+++ b/static/app/views/dashboards/widgetBuilder/buildSteps/groupByStep/groupBySelector.tsx
@@ -129,9 +129,7 @@ export function GroupBySelector({
     }>(
       (acc, key) => {
         const value = fieldOptions[key]!;
-        const optionInColumnsIndex = columnFieldsAsString.findIndex(
-          column => column === value.value.meta.name
-        );
+        const optionInColumnsIndex = columnFieldsAsString.indexOf(value.value.meta.name);
         if (optionInColumnsIndex === -1) {
           acc.filteredFieldOptions[key] = value;
           return acc;
diff --git a/static/app/views/projectDetail/projectCharts.tsx b/static/app/views/projectDetail/projectCharts.tsx
index 972e85be9e224c..d7b282421b22e8 100644
--- a/static/app/views/projectDetail/projectCharts.tsx
+++ b/static/app/views/projectDetail/projectCharts.tsx
@@ -124,7 +124,7 @@ class ProjectCharts extends Component<Props, State> {
       .map(urlKey => {
         return decodeScalar(
           location.query[urlKey],
-          this.defaultDisplayModes[visibleCharts.findIndex(value => value === urlKey)]!
+          this.defaultDisplayModes[visibleCharts.indexOf(urlKey)]!
         );
       });
   }