diff --git a/packages/react-router/__tests__/router/fetchers-test.ts b/packages/react-router/__tests__/router/fetchers-test.ts
index 504e68d750..2fa7b1c0b5 100644
--- a/packages/react-router/__tests__/router/fetchers-test.ts
+++ b/packages/react-router/__tests__/router/fetchers-test.ts
@@ -169,7 +169,7 @@ describe("fetchers", () => {
         formData: createFormData({ key: "value" }),
       });
       expect(A.fetcher.state).toBe("loading");
-      expect(A.fetcher.formMethod).toBe("get");
+      expect(A.fetcher.formMethod).toBe("GET");
       expect(A.fetcher.formAction).toBe("/foo");
       expect(A.fetcher.formData).toEqual(createFormData({ key: "value" }));
       expect(A.fetcher.formEncType).toBe("application/x-www-form-urlencoded");
@@ -2111,7 +2111,7 @@ describe("fetchers", () => {
           "formAction": "/two/three",
           "formData": FormData {},
           "formEncType": "application/x-www-form-urlencoded",
-          "formMethod": "post",
+          "formMethod": "POST",
           "json": undefined,
           "nextParams": {
             "a": "two",
diff --git a/packages/react-router/__tests__/router/navigation-test.ts b/packages/react-router/__tests__/router/navigation-test.ts
index a21cc3dcfa..909cff68f8 100644
--- a/packages/react-router/__tests__/router/navigation-test.ts
+++ b/packages/react-router/__tests__/router/navigation-test.ts
@@ -1154,7 +1154,7 @@ describe("navigations", () => {
         // @ts-expect-error
         new URLSearchParams(navigation.formData).toString()
       ).toBe("gosh=dang");
-      expect(navigation.formMethod).toBe("post");
+      expect(navigation.formMethod).toBe("POST");
       expect(navigation.formEncType).toBe("application/x-www-form-urlencoded");
       expect(navigation.location).toMatchObject({
         pathname: "/foo",
@@ -1169,7 +1169,7 @@ describe("navigations", () => {
         // @ts-expect-error
         new URLSearchParams(navigation.formData).toString()
       ).toBe("gosh=dang");
-      expect(navigation.formMethod).toBe("post");
+      expect(navigation.formMethod).toBe("POST");
       expect(navigation.formEncType).toBe("application/x-www-form-urlencoded");
       expect(navigation.location).toMatchObject({
         pathname: "/foo",
@@ -1203,7 +1203,7 @@ describe("navigations", () => {
         // @ts-expect-error
         new URLSearchParams(navigation.formData).toString()
       ).toBe("gosh=dang");
-      expect(navigation.formMethod).toBe("post");
+      expect(navigation.formMethod).toBe("POST");
       expect(navigation.location).toMatchObject({
         pathname: "/bar",
         search: "",
@@ -1229,7 +1229,7 @@ describe("navigations", () => {
       let navigation = t.router.state.navigation;
       expect(navigation.state).toBe("loading");
       expect(navigation.formData).toEqual(createFormData({ gosh: "dang" }));
-      expect(navigation.formMethod).toBe("get");
+      expect(navigation.formMethod).toBe("GET");
       expect(navigation.formEncType).toBe("application/x-www-form-urlencoded");
       expect(navigation.location).toMatchObject({
         pathname: "/foo",
@@ -1257,7 +1257,7 @@ describe("navigations", () => {
       let navigation = t.router.state.navigation;
       expect(navigation.state).toBe("loading");
       expect(navigation.formData).toEqual(createFormData({ gosh: "dang" }));
-      expect(navigation.formMethod).toBe("get");
+      expect(navigation.formMethod).toBe("GET");
       expect(navigation.formEncType).toBe("application/x-www-form-urlencoded");
       expect(navigation.location?.pathname).toBe("/bar");
 
diff --git a/packages/react-router/__tests__/router/revalidate-test.ts b/packages/react-router/__tests__/router/revalidate-test.ts
index 8f15661e36..3255fd4397 100644
--- a/packages/react-router/__tests__/router/revalidate-test.ts
+++ b/packages/react-router/__tests__/router/revalidate-test.ts
@@ -271,7 +271,7 @@ describe("router.revalidate", () => {
           pathname: "/tasks",
           search: "?key=value",
         },
-        formMethod: "get",
+        formMethod: "GET",
         formData: createFormData({ key: "value" }),
       },
       revalidation: "loading",
diff --git a/packages/react-router/__tests__/router/router-test.ts b/packages/react-router/__tests__/router/router-test.ts
index 929c075460..49ba868309 100644
--- a/packages/react-router/__tests__/router/router-test.ts
+++ b/packages/react-router/__tests__/router/router-test.ts
@@ -690,7 +690,7 @@ describe("a router", () => {
         pathname: "/tasks",
         search: "?key=value",
       });
-      expect(t.router.state.navigation.formMethod).toBe("get");
+      expect(t.router.state.navigation.formMethod).toBe("GET");
       expect(t.router.state.navigation.formData).toEqual(
         createFormData({ key: "value" })
       );
@@ -710,7 +710,7 @@ describe("a router", () => {
         pathname: "/tasks",
         search: "?key=value",
       });
-      expect(t.router.state.navigation.formMethod).toBe("get");
+      expect(t.router.state.navigation.formMethod).toBe("GET");
       expect(t.router.state.navigation.formData).toEqual(
         createFormData({ key: "value" })
       );
@@ -730,7 +730,7 @@ describe("a router", () => {
         pathname: "/tasks",
         search: "?key=2",
       });
-      expect(t.router.state.navigation.formMethod).toBe("get");
+      expect(t.router.state.navigation.formMethod).toBe("GET");
       expect(t.router.state.navigation.formData).toEqual(
         createFormData({ key: "2" })
       );
@@ -750,7 +750,7 @@ describe("a router", () => {
         pathname: "/tasks",
         search: "?key=1",
       });
-      expect(t.router.state.navigation.formMethod).toBe("post");
+      expect(t.router.state.navigation.formMethod).toBe("POST");
       expect(t.router.state.navigation.formData).toEqual(
         createFormData({ key: "2" })
       );
diff --git a/packages/react-router/__tests__/router/should-revalidate-test.ts b/packages/react-router/__tests__/router/should-revalidate-test.ts
index f1aebc5f38..69037af7ed 100644
--- a/packages/react-router/__tests__/router/should-revalidate-test.ts
+++ b/packages/react-router/__tests__/router/should-revalidate-test.ts
@@ -256,7 +256,7 @@ describe("shouldRevalidate", () => {
       nextParams: {},
       nextUrl: expect.urlMatch("http://localhost/child"),
       defaultShouldRevalidate: true,
-      formMethod: "post",
+      formMethod: "POST",
       formAction: "/child",
       formEncType: "application/x-www-form-urlencoded",
       actionResult: "ACTION",
@@ -310,7 +310,7 @@ describe("shouldRevalidate", () => {
       nextParams: {},
       nextUrl: expect.urlMatch("http://localhost/"),
       defaultShouldRevalidate: true,
-      formMethod: "post",
+      formMethod: "POST",
       formAction: "/child",
       formEncType: "application/x-www-form-urlencoded",
       actionResult: undefined,
@@ -364,7 +364,7 @@ describe("shouldRevalidate", () => {
       nextParams: {},
       nextUrl: expect.urlMatch("http://localhost/child"),
       defaultShouldRevalidate: true,
-      formMethod: "post",
+      formMethod: "POST",
       formAction: "/child",
       formEncType: "application/x-www-form-urlencoded",
       actionResult: "ACTION",
@@ -406,7 +406,7 @@ describe("shouldRevalidate", () => {
     // @ts-expect-error
     let arg = shouldRevalidate.mock.calls[0][0];
     let expectedArg: Partial<ShouldRevalidateFunctionArgs> = {
-      formMethod: "post",
+      formMethod: "POST",
       formAction: "/",
       formEncType: "application/json",
       text: undefined,
@@ -448,7 +448,7 @@ describe("shouldRevalidate", () => {
     // @ts-expect-error
     let arg = shouldRevalidate.mock.calls[0][0];
     let expectedArg: Partial<ShouldRevalidateFunctionArgs> = {
-      formMethod: "post",
+      formMethod: "POST",
       formAction: "/",
       formEncType: "text/plain",
       text: "hello world",
@@ -657,7 +657,7 @@ describe("shouldRevalidate", () => {
       formAction: "/child",
       formData: createFormData({}),
       formEncType: "application/x-www-form-urlencoded",
-      formMethod: "post",
+      formMethod: "POST",
       defaultShouldRevalidate: true,
     });
 
@@ -715,7 +715,7 @@ describe("shouldRevalidate", () => {
         "formAction": "/fetch",
         "formData": FormData {},
         "formEncType": "application/x-www-form-urlencoded",
-        "formMethod": "post",
+        "formMethod": "POST",
         "json": undefined,
         "nextParams": {},
         "nextUrl": "http://localhost/",
@@ -779,7 +779,7 @@ describe("shouldRevalidate", () => {
         "formAction": "/fetch",
         "formData": FormData {},
         "formEncType": "application/x-www-form-urlencoded",
-        "formMethod": "post",
+        "formMethod": "POST",
         "json": undefined,
         "nextParams": {},
         "nextUrl": "http://localhost/",
diff --git a/packages/react-router/__tests__/router/submission-test.ts b/packages/react-router/__tests__/router/submission-test.ts
index 520e57fc33..8c49a593b4 100644
--- a/packages/react-router/__tests__/router/submission-test.ts
+++ b/packages/react-router/__tests__/router/submission-test.ts
@@ -504,16 +504,16 @@ describe("submissions", () => {
           formMethod: "get",
           formData: createFormData({}),
         });
-        expect(t.router.state.navigation.formMethod).toBe("get");
+        expect(t.router.state.navigation.formMethod).toBe("GET");
         await A.loaders.child.resolve("LOADER");
         expect(t.router.state.navigation.formMethod).toBeUndefined();
         await t.router.navigate("/");
 
         let B = await t.navigate("/child", {
-          formMethod: "POST",
+          formMethod: "post",
           formData: createFormData({}),
         });
-        expect(t.router.state.navigation.formMethod).toBe("post");
+        expect(t.router.state.navigation.formMethod).toBe("POST");
         await B.actions.child.resolve("ACTION");
         await B.loaders.child.resolve("LOADER");
         expect(t.router.state.navigation.formMethod).toBeUndefined();
@@ -523,15 +523,15 @@ describe("submissions", () => {
           formMethod: "GET",
           formData: createFormData({}),
         });
-        expect(t.router.state.fetchers.get("key")?.formMethod).toBe("get");
+        expect(t.router.state.fetchers.get("key")?.formMethod).toBe("GET");
         await C.loaders.child.resolve("LOADER FETCH");
         expect(t.router.state.fetchers.get("key")?.formMethod).toBeUndefined();
 
         let D = await t.fetch("/child", "key", {
-          formMethod: "post",
+          formMethod: "POST",
           formData: createFormData({}),
         });
-        expect(t.router.state.fetchers.get("key")?.formMethod).toBe("post");
+        expect(t.router.state.fetchers.get("key")?.formMethod).toBe("POST");
         await D.actions.child.resolve("ACTION FETCH");
         expect(t.router.state.fetchers.get("key")?.formMethod).toBeUndefined();
       });