diff --git a/changelog.d/fixes/11718-peak-hour-overnight-days.md b/changelog.d/fixes/11718-peak-hour-overnight-days.md
new file mode 100644
index 0000000000..296d27c3e4
--- /dev/null
+++ b/changelog.d/fixes/11718-peak-hour-overnight-days.md
@@ -0,0 +1 @@
+- **fix(providers):** Keep overnight peak-hour protection active after midnight according to the window's configured start day ([#11718](https://github.com/diegosouzapw/OmniRoute/pull/11718)) — thanks @pacocartones
diff --git a/src/lib/providers/peakHourProtection.ts b/src/lib/providers/peakHourProtection.ts
index 08bf6248dd..5957cc340e 100644
--- a/src/lib/providers/peakHourProtection.ts
+++ b/src/lib/providers/peakHourProtection.ts
@@ -109,11 +109,13 @@ function isDayAllowed(window: PeakHourWindow, date: Date): boolean {
 }
 
 function windowActiveAt(window: PeakHourWindow, date: Date): boolean {
-  if (!isDayAllowed(window, date)) return false;
   const start = parseUtcTimeMinutes(window.startUtc);
   const end = parseUtcTimeMinutes(window.endUtc);
   if (start === null || end === null || start === end) return false;
   const now = date.getUTCHours() * 60 + date.getUTCMinutes();
+  const effectiveDay =
+    start > end && now < end ? new Date(date.getTime() - MINUTES_PER_DAY * 60_000) : date;
+  if (!isDayAllowed(window, effectiveDay)) return false;
   return start < end ? now >= start && now < end : now >= start || now < end;
 }
 
diff --git a/tests/unit/peak-hour-protection.test.ts b/tests/unit/peak-hour-protection.test.ts
index 0b58ef6479..fc474edaae 100644
--- a/tests/unit/peak-hour-protection.test.ts
+++ b/tests/unit/peak-hour-protection.test.ts
@@ -55,6 +55,73 @@ test("peak-hour protection honors weekdays and end boundary", () => {
   );
 });
 
+test("overnight windows apply their start day after midnight", () => {
+  const mondayWindow = {
+    peakHourProtection: {
+      enabled: true,
+      mode: "block",
+      windows: [{ days: ["mon"], startUtc: "22:00", endUtc: "02:00" }],
+    },
+  };
+
+  const mondayNight = evaluatePeakHourProtection(
+    mondayWindow,
+    new Date("2026-08-24T23:00:00.000Z")
+  );
+  assert.equal(mondayNight.active, true);
+  assert.equal(mondayNight.retryAfter, "2026-08-25T02:00:00.000Z");
+
+  const tuesdayEarly = evaluatePeakHourProtection(
+    mondayWindow,
+    new Date("2026-08-25T01:00:00.000Z")
+  );
+  assert.equal(tuesdayEarly.active, true);
+  assert.equal(tuesdayEarly.retryAfter, "2026-08-25T02:00:00.000Z");
+
+  assert.deepEqual(evaluatePeakHourProtection(mondayWindow, new Date("2026-08-25T02:00:00.000Z")), {
+    active: false,
+  });
+  assert.deepEqual(evaluatePeakHourProtection(mondayWindow, new Date("2026-08-25T23:00:00.000Z")), {
+    active: false,
+  });
+
+  const tuesdayWindow = {
+    peakHourProtection: {
+      enabled: true,
+      mode: "block",
+      windows: [{ days: ["tue"], startUtc: "22:00", endUtc: "02:00" }],
+    },
+  };
+  assert.deepEqual(
+    evaluatePeakHourProtection(tuesdayWindow, new Date("2026-08-25T01:00:00.000Z")),
+    { active: false }
+  );
+
+  const sundayWindow = {
+    peakHourProtection: {
+      enabled: true,
+      mode: "block",
+      windows: [{ days: ["sun"], startUtc: "22:00", endUtc: "02:00" }],
+    },
+  };
+  assert.equal(
+    evaluatePeakHourProtection(sundayWindow, new Date("2026-08-24T01:00:00.000Z")).active,
+    true
+  );
+
+  const dailyWindow = {
+    peakHourProtection: {
+      enabled: true,
+      mode: "block",
+      windows: [{ startUtc: "22:00", endUtc: "02:00" }],
+    },
+  };
+  assert.equal(
+    evaluatePeakHourProtection(dailyWindow, new Date("2026-08-25T01:00:00.000Z")).active,
+    true
+  );
+});
+
 test("peak-hour protection supports daily Z.ai-style windows", () => {
   const state = evaluatePeakHourProtection(
     {