diff --git a/shell/browser/native_window_views.cc b/shell/browser/native_window_views.cc
index e5320308a2dc..44de6c197f09 100644
--- a/shell/browser/native_window_views.cc
+++ b/shell/browser/native_window_views.cc
@@ -642,8 +642,22 @@ void NativeWindowViews::SetEnabledInternal(bool enable) {
 #endif
 }
 
-#if BUILDFLAG(IS_LINUX)
 void NativeWindowViews::Maximize() {
+#if BUILDFLAG(IS_WIN)
+  if (IsTranslucent()) {
+    // If a window is translucent but not transparent on Windows,
+    // that means it must have a backgroundMaterial set.
+    if (!transparent())
+      SetRoundedCorners(false);
+    restore_bounds_ = GetBounds();
+    auto display = display::Screen::GetScreen()->GetDisplayNearestWindow(
+        GetNativeWindow());
+    SetBounds(display.work_area(), false);
+    NotifyWindowMaximize();
+    return;
+  }
+#endif
+
   if (IsVisible()) {
     widget()->Maximize();
   } else {
@@ -652,44 +666,46 @@ void NativeWindowViews::Maximize() {
     NotifyWindowShow();
   }
 }
-#endif
 
 void NativeWindowViews::Unmaximize() {
-  if (IsMaximized()) {
+  if (!IsMaximized())
+    return;
+
 #if BUILDFLAG(IS_WIN)
+  if (IsTranslucent()) {
+    SetBounds(restore_bounds_, false);
+    NotifyWindowUnmaximize();
     if (transparent()) {
-      SetBounds(restore_bounds_, false);
-      NotifyWindowUnmaximize();
       UpdateThickFrame();
-      return;
+    } else {
+      SetRoundedCorners(true);
     }
+    return;
+  }
 #endif
 
-    widget()->Restore();
+  widget()->Restore();
 
 #if BUILDFLAG(IS_WIN)
-    UpdateThickFrame();
+  UpdateThickFrame();
 #endif
-  }
 }
 
 bool NativeWindowViews::IsMaximized() const {
-  if (widget()->IsMaximized()) {
+  if (widget()->IsMaximized())
     return true;
-  } else {
+
 #if BUILDFLAG(IS_WIN)
-    if (transparent() && !IsMinimized()) {
-      // Compare the size of the window with the size of the display
-      auto display = display::Screen::GetScreen()->GetDisplayNearestWindow(
-          GetNativeWindow());
-      // Maximized if the window is the same dimensions and placement as the
-      // display
-      return GetBounds() == display.work_area();
-    }
+  if (IsTranslucent() && !IsMinimized()) {
+    // If the window is the same dimensions and placement as the
+    // display, we consider it maximized.
+    auto display = display::Screen::GetScreen()->GetDisplayNearestWindow(
+        GetNativeWindow());
+    return GetBounds() == display.work_area();
+  }
 #endif
 
-    return false;
-  }
+  return false;
 }
 
 void NativeWindowViews::Minimize() {
@@ -702,10 +718,14 @@ void NativeWindowViews::Minimize() {
 
 void NativeWindowViews::Restore() {
 #if BUILDFLAG(IS_WIN)
-  if (IsMaximized() && transparent()) {
+  if (IsMaximized() && IsTranslucent()) {
     SetBounds(restore_bounds_, false);
     NotifyWindowRestore();
-    UpdateThickFrame();
+    if (transparent()) {
+      UpdateThickFrame();
+    } else {
+      SetRoundedCorners(true);
+    }
     return;
   }
 #endif
@@ -845,7 +865,7 @@ gfx::Size NativeWindowViews::GetContentSize() const {
 
 gfx::Rect NativeWindowViews::GetNormalBounds() const {
 #if BUILDFLAG(IS_WIN)
-  if (IsMaximized() && transparent())
+  if (IsMaximized() && IsTranslucent())
     return restore_bounds_;
 #endif
   return widget()->GetRestoredBounds();
@@ -860,8 +880,8 @@ void NativeWindowViews::SetContentSizeConstraints(
   if (!thick_frame_)
     return;
 #endif
-  // widget_delegate() is only available after Init() is called, we make use of
-  // this to determine whether native widget has initialized.
+  // widget_delegate() is only available after Init() is called, we make use
+  // of this to determine whether native widget has initialized.
   if (widget() && widget()->widget_delegate())
     widget()->OnSizeConstraintsChanged();
   if (resizable_)
@@ -1639,9 +1659,9 @@ void NativeWindowViews::UpdateThickFrame() {
     return;
 
   if (IsMaximized() && !transparent()) {
-    // For maximized window add thick frame always, otherwise it will be removed
-    // in HWNDMessageHandler::SizeConstraintsChanged() which will result in
-    // maximized window bounds change.
+    // For maximized window add thick frame always, otherwise it will be
+    // removed in HWNDMessageHandler::SizeConstraintsChanged() which will
+    // result in maximized window bounds change.
     FlipWindowStyle(GetAcceleratedWidget(), true, WS_THICKFRAME);
   } else if (has_frame()) {
     FlipWindowStyle(GetAcceleratedWidget(), resizable_, WS_THICKFRAME);
@@ -1679,10 +1699,10 @@ void NativeWindowViews::OnWidgetBoundsChanged(views::Widget* changed_widget,
   // WidgetObserver::OnWidgetBoundsChanged is being called from
   // Widget::OnNativeWidgetMove() and not Widget::OnNativeWidgetSizeChanged.
   // |GetWindowBoundsInScreen| has a ~1 pixel margin
-  // of error because it converts from floats to integers between calculations,
-  // so if we check existing bounds directly against the new bounds without
-  // accounting for that we'll have constant false positives when the window is
-  // moving but the user hasn't changed its size at all.
+  // of error because it converts from floats to integers between
+  // calculations, so if we check existing bounds directly against the new
+  // bounds without accounting for that we'll have constant false positives
+  // when the window is moving but the user hasn't changed its size at all.
   auto isWithinOnePixel = [](gfx::Size old_size, gfx::Size new_size) -> bool {
     return base::IsApproximatelyEqual(old_size.width(), new_size.width(), 1) &&
            base::IsApproximatelyEqual(old_size.height(), new_size.height(), 1);
@@ -1807,8 +1827,8 @@ void NativeWindowViews::OnMouseEvent(ui::MouseEvent* event) {
 ui::mojom::WindowShowState NativeWindowViews::GetRestoredState() {
   if (IsMaximized()) {
 #if BUILDFLAG(IS_WIN)
-    // Only restore Maximized state when window is NOT transparent style
-    if (!transparent()) {
+    // Restore maximized state for windows that are not translucent.
+    if (!IsTranslucent()) {
       return ui::mojom::WindowShowState::kMaximized;
     }
 #else
diff --git a/shell/browser/native_window_views.h b/shell/browser/native_window_views.h
index 05c7bbc866fe..fe2c3a197b11 100644
--- a/shell/browser/native_window_views.h
+++ b/shell/browser/native_window_views.h
@@ -202,11 +202,9 @@ class NativeWindowViews : public NativeWindow,
   void OnWidgetMove() override;
 #if BUILDFLAG(IS_WIN)
   bool ExecuteWindowsCommand(int command_id) override;
-#endif
-
-#if BUILDFLAG(IS_WIN)
   void HandleSizeEvent(WPARAM w_param, LPARAM l_param);
   void ResetWindowControls();
+  void SetRoundedCorners(bool rounded);
   void SetForwardMouseMessages(bool forward);
   static LRESULT CALLBACK SubclassProc(HWND hwnd,
                                        UINT msg,
diff --git a/shell/browser/native_window_views_win.cc b/shell/browser/native_window_views_win.cc
index 9857d93b22f1..91bd2413ce6e 100644
--- a/shell/browser/native_window_views_win.cc
+++ b/shell/browser/native_window_views_win.cc
@@ -8,6 +8,7 @@
 
 #include "base/win/atl.h"  // Must be before UIAutomationCore.h
 #include "base/win/scoped_handle.h"
+#include "base/win/windows_version.h"
 #include "content/public/browser/browser_accessibility_state.h"
 #include "shell/browser/browser.h"
 #include "shell/browser/native_window_views.h"
@@ -225,25 +226,6 @@ bool IsScreenReaderActive() {
 std::set<NativeWindowViews*> NativeWindowViews::forwarding_windows_;
 HHOOK NativeWindowViews::mouse_hook_ = nullptr;
 
-void NativeWindowViews::Maximize() {
-  // Only use Maximize() when window is NOT transparent style
-  if (!transparent()) {
-    if (IsVisible()) {
-      widget()->Maximize();
-    } else {
-      widget()->native_widget_private()->Show(
-          ui::mojom::WindowShowState::kMaximized, gfx::Rect());
-      NotifyWindowShow();
-    }
-  } else {
-    restore_bounds_ = GetBounds();
-    auto display = display::Screen::GetScreen()->GetDisplayNearestWindow(
-        GetNativeWindow());
-    SetBounds(display.work_area(), false);
-    NotifyWindowMaximize();
-  }
-}
-
 bool NativeWindowViews::ExecuteWindowsCommand(int command_id) {
   const auto command_name = AppCommandToString(command_id);
   NotifyWindowExecuteAppCommand(command_name);
@@ -535,6 +517,24 @@ void NativeWindowViews::ResetWindowControls() {
   }
 }
 
+// Windows with |backgroundMaterial| expand to the same dimensions and
+// placement as the display to approximate maximization - unless we remove
+// rounded corners there will be a gap between the window and the display
+// at the corners noticable to users.
+void NativeWindowViews::SetRoundedCorners(bool rounded) {
+  // DWMWA_WINDOW_CORNER_PREFERENCE is supported after Windows 11 Build 22000.
+  if (base::win::GetVersion() < base::win::Version::WIN11)
+    return;
+
+  DWM_WINDOW_CORNER_PREFERENCE round_pref =
+      rounded ? DWMWCP_ROUND : DWMWCP_DONOTROUND;
+  HRESULT result = DwmSetWindowAttribute(GetAcceleratedWidget(),
+                                         DWMWA_WINDOW_CORNER_PREFERENCE,
+                                         &round_pref, sizeof(round_pref));
+  if (FAILED(result))
+    LOG(WARNING) << "Failed to set rounded corners to " << rounded;
+}
+
 void NativeWindowViews::SetForwardMouseMessages(bool forward) {
   if (forward && !forwarding_mouse_messages_) {
     forwarding_mouse_messages_ = true;