diff --git a/src/frontend-common/cheevos.cpp b/src/frontend-common/cheevos.cpp
index 45d5d877f..d7322c0fc 100644
--- a/src/frontend-common/cheevos.cpp
+++ b/src/frontend-common/cheevos.cpp
@@ -590,6 +590,19 @@ static void DisplayAchievementSummary()
   {
     summary = GetHostInterface()->TranslateString("Cheevos", "This game has no achievements.");
   }
+  if (GetLeaderboardCount() > 0)
+  {
+    summary.push_back('\n');
+    if (g_challenge_mode)
+    {
+      summary.append(GetHostInterface()->TranslateString("Cheevos", "Leaderboards are enabled."));
+    }
+    else
+    {
+      summary.append(
+        GetHostInterface()->TranslateString("Cheevos", "Leaderboards are DISABLED because Hardcore Mode is off."));
+    }
+  }
 
   ImGuiFullscreen::AddNotification(10.0f, std::move(title), std::move(summary), s_game_icon);
 }
@@ -1350,6 +1363,13 @@ void SubmitLeaderboard(u32 leaderboard_id, int value)
     return;
   }
 
+  if (!g_challenge_mode)
+  {
+    Log_WarningPrintf("Skipping sending leaderboard %u result to server because Challenge mode is off.",
+                      leaderboard_id);
+    return;
+  }
+
   char url[512];
   rc_url_submit_lboard(url, sizeof(url), s_username.c_str(), s_login_token.c_str(), leaderboard_id, value);
   s_http_downloader->CreateRequest(url, SubmitLeaderboardCallback);
diff --git a/src/frontend-common/fullscreen_ui.cpp b/src/frontend-common/fullscreen_ui.cpp
index 33bb305d6..a506f7b39 100644
--- a/src/frontend-common/fullscreen_ui.cpp
+++ b/src/frontend-common/fullscreen_ui.cpp
@@ -4505,6 +4505,18 @@ void DrawLeaderboardsWindow()
       ImGui::PushFont(g_medium_font);
       ImGui::RenderTextClipped(summary_bb.Min, summary_bb.Max, text.GetCharArray(),
                                text.GetCharArray() + text.GetLength(), nullptr, ImVec2(0.0f, 0.0f), &summary_bb);
+
+      if (!IsCheevosHardcoreModeActive())
+      {
+        const ImRect hardcore_warning_bb(ImVec2(left, top), ImVec2(right, top + g_medium_font->FontSize));
+        top += g_medium_font->FontSize + spacing;
+
+        ImGui::RenderTextClipped(
+          hardcore_warning_bb.Min, hardcore_warning_bb.Max,
+          "Submitting scores is DISABLED because Hardcore Mode is off. Leaderboards are read-only.", nullptr, nullptr,
+          ImVec2(0.0f, 0.0f), &hardcore_warning_bb);
+      }
+
       ImGui::PopFont();
     }