diff --git a/routers/web/auth/auth.go b/routers/web/auth/auth.go
index 04e410543d2ce..da6bef207ad7c 100644
--- a/routers/web/auth/auth.go
+++ b/routers/web/auth/auth.go
@@ -123,9 +123,21 @@ func resetLocale(ctx *context.Context, u *user_model.User) error {
 	return nil
 }
 
+func RedirectAfterLogin(ctx *context.Context) {
+	redirectTo := ctx.FormString("redirect_to")
+	if redirectTo == "" {
+		redirectTo = ctx.GetSiteCookie("redirect_to")
+	}
+	middleware.DeleteRedirectToCookie(ctx.Resp)
+	nextRedirectTo := setting.AppSubURL + string(setting.LandingPageURL)
+	if setting.LandingPageURL == setting.LandingPageLogin {
+		nextRedirectTo = setting.AppSubURL + "/" // do not cycle-redirect to the login page
+	}
+	ctx.RedirectToFirst(redirectTo, nextRedirectTo)
+}
+
 func CheckAutoLogin(ctx *context.Context) bool {
-	// Check auto-login
-	isSucceed, err := autoSignIn(ctx)
+	isSucceed, err := autoSignIn(ctx) // try to auto-login
 	if err != nil {
 		if errors.Is(err, auth_service.ErrAuthTokenInvalidHash) {
 			ctx.Flash.Error(ctx.Tr("auth.remember_me.compromised"), true)
@@ -138,17 +150,10 @@ func CheckAutoLogin(ctx *context.Context) bool {
 	redirectTo := ctx.FormString("redirect_to")
 	if len(redirectTo) > 0 {
 		middleware.SetRedirectToCookie(ctx.Resp, redirectTo)
-	} else {
-		redirectTo = ctx.GetSiteCookie("redirect_to")
 	}
 
 	if isSucceed {
-		middleware.DeleteRedirectToCookie(ctx.Resp)
-		nextRedirectTo := setting.AppSubURL + string(setting.LandingPageURL)
-		if setting.LandingPageURL == setting.LandingPageLogin {
-			nextRedirectTo = setting.AppSubURL + "/" // do not cycle-redirect to the login page
-		}
-		ctx.RedirectToFirst(redirectTo, nextRedirectTo)
+		RedirectAfterLogin(ctx)
 		return true
 	}
 
@@ -163,6 +168,11 @@ func SignIn(ctx *context.Context) {
 		return
 	}
 
+	if ctx.IsSigned {
+		RedirectAfterLogin(ctx)
+		return
+	}
+
 	oauth2Providers, err := oauth2.GetOAuth2Providers(ctx, optional.Some(true))
 	if err != nil {
 		ctx.ServerError("UserSignIn", err)
diff --git a/routers/web/auth/auth_test.go b/routers/web/auth/auth_test.go
new file mode 100644
index 0000000000000..c4e583c7e5183
--- /dev/null
+++ b/routers/web/auth/auth_test.go
@@ -0,0 +1,38 @@
+// Copyright 2024 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package auth
+
+import (
+	"net/http"
+	"net/url"
+	"testing"
+
+	"code.gitea.io/gitea/modules/test"
+	"code.gitea.io/gitea/services/contexttest"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestUserLogin(t *testing.T) {
+	ctx, resp := contexttest.MockContext(t, "/user/login")
+	ctx.IsSigned = true
+	SignIn(ctx)
+	assert.Equal(t, "/", test.RedirectURL(resp))
+
+	ctx, resp = contexttest.MockContext(t, "/user/login?redirect_to=/other")
+	ctx.IsSigned = true
+	SignIn(ctx)
+	assert.Equal(t, "/other", test.RedirectURL(resp))
+
+	ctx, resp = contexttest.MockContext(t, "/user/login")
+	ctx.Req.AddCookie(&http.Cookie{Name: "redirect_to", Value: "/other-cookie"})
+	ctx.IsSigned = true
+	SignIn(ctx)
+	assert.Equal(t, "/other-cookie", test.RedirectURL(resp))
+
+	ctx, resp = contexttest.MockContext(t, "/user/login?redirect_to="+url.QueryEscape("https://example.com"))
+	ctx.IsSigned = true
+	SignIn(ctx)
+	assert.Equal(t, "/", test.RedirectURL(resp))
+}
diff --git a/services/contexttest/context_tests.go b/services/contexttest/context_tests.go
index 431017a30dcb6..d3e6de7efe4f9 100644
--- a/services/contexttest/context_tests.go
+++ b/services/contexttest/context_tests.go
@@ -7,6 +7,7 @@ package contexttest
 import (
 	gocontext "context"
 	"io"
+	"maps"
 	"net/http"
 	"net/http/httptest"
 	"net/url"
@@ -36,7 +37,7 @@ func mockRequest(t *testing.T, reqPath string) *http.Request {
 	}
 	requestURL, err := url.Parse(path)
 	assert.NoError(t, err)
-	req := &http.Request{Method: method, URL: requestURL, Form: url.Values{}}
+	req := &http.Request{Method: method, URL: requestURL, Form: maps.Clone(requestURL.Query()), Header: http.Header{}}
 	req = req.WithContext(middleware.WithContextData(req.Context()))
 	return req
 }