diff --git a/browser/ui/views/frame/vertical_tab_strip_region_view.cc b/browser/ui/views/frame/vertical_tab_strip_region_view.cc
index 22b69d5fd1c0..630853416843 100644
--- a/browser/ui/views/frame/vertical_tab_strip_region_view.cc
+++ b/browser/ui/views/frame/vertical_tab_strip_region_view.cc
@@ -918,13 +918,7 @@ void VerticalTabStripRegionView::Layout(PassKey) {
   // As we have to update ScrollView's viewport size and its contents size,
   // laying out children manually will be more handy.
 
-  // 1. New tab should be fixed at the bottom of container.
   const auto contents_bounds = GetContentsBounds();
-  new_tab_button_->SetSize(
-      {contents_bounds.width(), new_tab_button_->GetPreferredSize().height()});
-  new_tab_button_->SetPosition(
-      {contents_bounds.x(),
-       contents_bounds.bottom() - new_tab_button_->height()});
 
   const gfx::Size header_size{contents_bounds.width(),
                               tabs::kVerticalTabHeight + kHeaderInset * 2};
@@ -932,11 +926,33 @@ void VerticalTabStripRegionView::Layout(PassKey) {
   header_view_->SetSize(header_size);
 
   contents_view_->SetSize(
-      {contents_bounds.width(), contents_bounds.height() -
-                                    new_tab_button_->height() -
-                                    header_view_->height()});
+      {contents_bounds.width(),
+       original_region_view_->tab_strip_->tab_container_->GetPreferredSize()
+           .height()});
+
   contents_view_->SetPosition({contents_bounds.origin().x(),
                                header_view_->y() + header_view_->height()});
+
+  int new_tab_height = new_tab_button_->GetPreferredSize().height();
+  new_tab_button_->SetSize(gfx::Size(contents_bounds.width(), new_tab_height));
+
+  int contents_view_max_height = contents_bounds.height() -
+                                 new_tab_button_->height() -
+                                 header_view_->height();
+
+  // Position New Tab Button and update the size of contents view if needed.
+  int contents_view_bottom_y = contents_view_->y() + contents_view_->height();
+  int new_tab_button_max_y = contents_bounds.bottom() - new_tab_height;
+  if (contents_view_bottom_y >= new_tab_button_max_y) {
+    contents_view_->SetSize(
+        gfx::Size(contents_bounds.width(), contents_view_max_height));
+    new_tab_button_->SetPosition(gfx::Point(
+        contents_bounds.x(), contents_bounds.bottom() - new_tab_height));
+  } else {
+    new_tab_button_->SetPosition(gfx::Point(
+        contents_bounds.x(), contents_view_->y() + contents_view_->height()));
+  }
+
   UpdateOriginalTabSearchButtonVisibility();
 
   // Put resize area, overlapped with contents.
diff --git a/browser/ui/views/tabs/brave_compound_tab_container.cc b/browser/ui/views/tabs/brave_compound_tab_container.cc
index 4cb1161da269..abd4f9ace87e 100644
--- a/browser/ui/views/tabs/brave_compound_tab_container.cc
+++ b/browser/ui/views/tabs/brave_compound_tab_container.cc
@@ -271,7 +271,11 @@ gfx::Size BraveCompoundTabContainer::CalculatePreferredSize(
   auto preferred_size =
       CompoundTabContainer::CalculatePreferredSize(available_size);
 
-  // Check if we can expand height to fill the entire scroll area's viewport.
+  const int combined_height =
+      pinned_tab_container_->GetPreferredSize().height() +
+      unpinned_tab_container_->GetPreferredSize().height();
+
+  // Traverse up the parent hierarchy to find the |VerticalTabStripRegionView|
   for (auto* parent_view = parent(); parent_view;
        parent_view = parent_view->parent()) {
     auto* region_view =
@@ -280,7 +284,8 @@ gfx::Size BraveCompoundTabContainer::CalculatePreferredSize(
       continue;
     }
 
-    preferred_size.set_height(region_view->GetTabStripViewportHeight());
+    preferred_size.set_height(
+        std::min(combined_height, region_view->GetTabStripViewportHeight()));
     break;
   }
 
diff --git a/browser/ui/views/tabs/brave_tab_strip.cc b/browser/ui/views/tabs/brave_tab_strip.cc
index f5bcd00083d8..9cea21086654 100644
--- a/browser/ui/views/tabs/brave_tab_strip.cc
+++ b/browser/ui/views/tabs/brave_tab_strip.cc
@@ -68,7 +68,11 @@ bool BraveTabStrip::IsVerticalTabsFloating() const {
   auto* vertical_region_view =
       browser_view->vertical_tab_strip_widget_delegate_view()
           ->vertical_tab_strip_region_view();
-  DCHECK(vertical_region_view);
+
+  if (!vertical_region_view) {
+    // Could be null while closing a window.
+    return false;
+  }
 
   return vertical_region_view->state() ==
              VerticalTabStripRegionView::State::kFloating ||