diff --git a/services/context/context_template.go b/services/context/context_template.go
index 2b34681faa..2c8fde6870 100644
--- a/services/context/context_template.go
+++ b/services/context/context_template.go
@@ -88,7 +88,7 @@ func (c TemplateContext) AppFullLink(link ...string) template.URL {
 	if len(link) == 0 {
 		return template.URL(s)
 	}
-	return template.URL(s + strings.TrimPrefix(link[0], "/"))
+	return template.URL(s + "/" + strings.TrimPrefix(link[0], "/"))
 }
 
 var globalVars = sync.OnceValue(func() (ret struct {
diff --git a/services/context/context_test.go b/services/context/context_test.go
index 54044644f0..aaf79de716 100644
--- a/services/context/context_test.go
+++ b/services/context/context_test.go
@@ -49,3 +49,17 @@ func TestRedirectToCurrentSite(t *testing.T) {
 		})
 	}
 }
+
+func TestAppFullLink(t *testing.T) {
+	setting.IsInTesting = true
+	defer test.MockVariableValue(&setting.AppURL, "https://gitea.example.com/sub/")()
+	defer test.MockVariableValue(&setting.AppSubURL, "/sub")()
+	defer test.MockVariableValue(&setting.PublicURLDetection, setting.PublicURLNever)()
+
+	req := httptest.NewRequest(http.MethodGet, "https://gitea.example.com/sub/", nil)
+	tmplCtx := NewTemplateContext(req.Context(), req)
+
+	assert.Equal(t, "https://gitea.example.com/sub", string(tmplCtx.AppFullLink()))
+	assert.Equal(t, "https://gitea.example.com/sub/user/repo", string(tmplCtx.AppFullLink("user/repo")))
+	assert.Equal(t, "https://gitea.example.com/sub/user/repo", string(tmplCtx.AppFullLink("/user/repo")))
+}