diff --git a/chrome/browser/ui/side_search/side_search_tab_contents_helper.cc b/chrome/browser/ui/side_search/side_search_tab_contents_helper.cc
index 7a7ecebbbbf251..4e22d34fd6dafe 100644
--- a/chrome/browser/ui/side_search/side_search_tab_contents_helper.cc
+++ b/chrome/browser/ui/side_search/side_search_tab_contents_helper.cc
@@ -23,6 +23,7 @@
 #include "services/network/public/cpp/simple_url_loader.h"
 #include "third_party/blink/public/mojom/frame/user_activation_notification_type.mojom.h"
 #include "ui/base/page_transition_types.h"
+#include "ui/views/controls/webview/web_contents_set_background_color.h"
 
 #if BUILDFLAG(ENABLE_EXTENSIONS)
 #include "chrome/browser/extensions/tab_helper.h"
@@ -175,6 +176,12 @@ void SideSearchTabContentsHelper::CreateSidePanelContents() {
   side_panel_contents_ =
       content::WebContents::Create(content::WebContents::CreateParams(
           web_contents()->GetBrowserContext(), nullptr));
+
+  // Apply a transparent background color so that we fallback to the hosting
+  // side panel view's background color.
+  views::WebContentsSetBackgroundColor::CreateForWebContentsWithColor(
+      side_panel_contents_.get(), SK_ColorTRANSPARENT);
+
   task_manager::WebContentsTags::CreateForTabContents(
       side_panel_contents_.get());
 
diff --git a/chrome/browser/ui/views/side_search/side_search_browser_controller.cc b/chrome/browser/ui/views/side_search/side_search_browser_controller.cc
index 5411e8b210db5a..db46987839b0aa 100644
--- a/chrome/browser/ui/views/side_search/side_search_browser_controller.cc
+++ b/chrome/browser/ui/views/side_search/side_search_browser_controller.cc
@@ -11,6 +11,7 @@
 #include "chrome/browser/feature_engagement/tracker_factory.h"
 #include "chrome/browser/ui/browser_element_identifiers.h"
 #include "chrome/browser/ui/chrome_pages.h"
+#include "chrome/browser/ui/color/chrome_color_id.h"
 #include "chrome/browser/ui/layout_constants.h"
 #include "chrome/browser/ui/page_action/page_action_icon_type.h"
 #include "chrome/browser/ui/side_search/side_search_utils.h"
@@ -284,6 +285,7 @@ views::WebView* ConfigureSidePanel(views::View* side_panel,
       views::kFlexBehaviorKey,
       views::FlexSpecification(views::MinimumFlexSizeRule::kScaleToZero,
                                views::MaximumFlexSizeRule::kUnbounded));
+  web_view->SetBackground(views::CreateThemedSolidBackground(kColorToolbar));
 
   side_panel->AddChildView(std::move(container));