diff --git a/.changeset/sour-roses-heal.md b/.changeset/sour-roses-heal.md
new file mode 100644
index 00000000000..f55b6553a80
--- /dev/null
+++ b/.changeset/sour-roses-heal.md
@@ -0,0 +1,5 @@
+---
+"@remix-run/react": patch
+---
+
+fix: preserve ?index for fetcher get submissions (#4238)
diff --git a/integration/fetcher-test.ts b/integration/fetcher-test.ts
index 950a8ee758b..39e6534a06b 100644
--- a/integration/fetcher-test.ts
+++ b/integration/fetcher-test.ts
@@ -10,6 +10,10 @@ test.describe("useFetcher", () => {
 
   let CHEESESTEAK = "CHEESESTEAK";
   let LUNCH = "LUNCH";
+  let PARENT_LAYOUT_LOADER = "parent layout loader";
+  let PARENT_LAYOUT_ACTION = "parent layout action";
+  let PARENT_INDEX_LOADER = "parent index loader";
+  let PARENT_INDEX_ACTION = "parent index action";
 
   test.beforeAll(async () => {
     fixture = await createFixture({
@@ -80,6 +84,65 @@ test.describe("useFetcher", () => {
             );
           }
         `,
+
+        "app/routes/parent.jsx": js`
+          import { Outlet } from "@remix-run/react";
+
+          export function action() {
+            return "${PARENT_LAYOUT_ACTION}";
+          };
+
+          export function loader() {
+            return "${PARENT_LAYOUT_LOADER}";
+          };
+
+          export default function Parent() {
+            return <Outlet />;
+          }
+        `,
+
+        "app/routes/parent/index.jsx": js`
+          import { useFetcher } from "@remix-run/react";
+
+          export function action() {
+            return "${PARENT_INDEX_ACTION}";
+          };
+
+          export function loader() {
+            return "${PARENT_INDEX_LOADER}";
+          };
+
+          export default function ParentIndex() {
+            let fetcher = useFetcher();
+
+            return (
+              <>
+                <pre>{fetcher.data}</pre>
+                <button id="load-parent" onClick={() => fetcher.load('/parent')}>
+                  Load parent
+                </button>
+                <button id="load-index" onClick={() => fetcher.load('/parent?index')}>
+                  Load index
+                </button>
+                <button id="submit-empty" onClick={() => fetcher.submit({})}>
+                  Submit empty
+                </button>
+                <button id="submit-parent-get" onClick={() => fetcher.submit({}, { method: 'get', action: '/parent' })}>
+                  Submit parent
+                </button>
+                <button id="submit-index-get" onClick={() => fetcher.submit({}, { method: 'get', action: '/parent?index' })}>
+                  Submit index
+                </button>
+                <button id="submit-parent-post" onClick={() => fetcher.submit({}, { method: 'post', action: '/parent' })}>
+                  Submit parent
+                </button>
+                <button id="submit-index-post" onClick={() => fetcher.submit({}, { method: 'post', action: '/parent?index' })}>
+                  Submit index
+                </button>
+              </>
+            );
+          }
+        `,
       },
     });
 
@@ -142,4 +205,31 @@ test.describe("useFetcher", () => {
     await app.clickElement("#fetcher-submit");
     expect(await app.getHtml("pre")).toMatch(CHEESESTEAK);
   });
+
+  test("fetchers handle ?index param correctly", async ({ page }) => {
+    let app = new PlaywrightFixture(appFixture, page);
+    await app.goto("/parent");
+
+    await app.clickElement("#load-parent");
+    expect(await app.getHtml("pre")).toMatch(PARENT_LAYOUT_LOADER);
+
+    await app.clickElement("#load-index");
+    expect(await app.getHtml("pre")).toMatch(PARENT_INDEX_LOADER);
+
+    // fetcher.submit({}) defaults to GET for the current Route
+    await app.clickElement("#submit-empty");
+    expect(await app.getHtml("pre")).toMatch(PARENT_INDEX_LOADER);
+
+    await app.clickElement("#submit-parent-get");
+    expect(await app.getHtml("pre")).toMatch(PARENT_LAYOUT_LOADER);
+
+    await app.clickElement("#submit-index-get");
+    expect(await app.getHtml("pre")).toMatch(PARENT_INDEX_LOADER);
+
+    await app.clickElement("#submit-parent-post");
+    expect(await app.getHtml("pre")).toMatch(PARENT_LAYOUT_ACTION);
+
+    await app.clickElement("#submit-index-post");
+    expect(await app.getHtml("pre")).toMatch(PARENT_INDEX_ACTION);
+  });
 });
diff --git a/packages/remix-react/components.tsx b/packages/remix-react/components.tsx
index 16641edf33c..0b39228f3b4 100644
--- a/packages/remix-react/components.tsx
+++ b/packages/remix-react/components.tsx
@@ -1233,6 +1233,16 @@ export function useSubmitImpl(key?: string): SubmitFunction {
             throw new Error(`Cannot submit binary form data using GET`);
           }
         }
+
+        // Preserve any incoming ?index param for fetcher GET submissions
+        let isIndexAction = new URLSearchParams(url.search)
+          .getAll("index")
+          .some((v) => v === "");
+        if (key != null && isIndexAction) {
+          hasParams = true;
+          params.append("index", "");
+        }
+
         url.search = hasParams ? `?${params.toString()}` : "";
       }