How to Change Firefox Themes: Install, Switch and Remove (2026)

Want to change Firefox themes? In 2007 we wrote about Personas for Firefox, a Mozilla Labs extension that gave your browser a new background instantly, with no restart. I loved how fast it was: pick one of 50+ designs and the toolbar and status bar changed on the spot. Mozilla later built Personas into Firefox itself, and today every Firefox theme works the same lightweight way. Here is how to find, install, switch and remove Firefox themes in 2026.

Quick answer: Open the Firefox menu (three lines) and choose Extensions and Themes, then Themes. Click Enable on a built-in theme (System, Light, Dark or Alpenglow), or browse Firefox Add-ons, open a theme and click Install Theme. It applies instantly with no restart. To go back, click Disable on your theme and Firefox returns to the System theme.

What happened to Firefox Personas?

Personas launched as an add-on that changed only the background image and colors of the browser frame, not the icons, which is why it could switch designs instantly. Designers could submit their own Personas without writing code. Mozilla folded the idea into Firefox as “lightweight themes,” and Personas eventually became simply Firefox themes. Old “complete” themes that redrew every icon are no longer supported, so all themes today are background-and-color themes, just like the original Personas.

How to change Firefox themes on desktop

Use a built-in theme

1. Click the menu button (three horizontal lines) at the top right.
2. Select Extensions and Themes, then click Themes on the left.
3. Click Enable next to System, Light, Dark or Alpenglow.

The System theme follows your computer’s light or dark mode automatically.

Install a new theme from Firefox Add-ons

1. Visit Firefox Add-ons themes (external site) or open Extensions and Themes > Recommendations.
2. Browse categories such as nature, scenery or abstract, or search for a color or topic.
3. Open a theme and click + Install Theme. It applies right away.

You can also pick a theme from the New Tab page: click the customize (pencil or gear) button at the bottom right and choose one under Appearance.

How to switch or remove a Firefox theme

• Switch: menu > Extensions and Themes > Themes, then click Enable on the theme you want. Installed themes stay in the list, so switching back is one click.
• Remove: click the three-dot icon next to a theme and choose Remove. If it was your active theme, Firefox goes back to the System theme.
• Reset to default: click Disable on your current theme.

Make your own Firefox theme

Like Personas once promised, you don’t need to code to design a theme:

• Firefox Color (external site) is a Mozilla extension that lets you pick colors for tabs, toolbars and the background, add a background image, and share your design with a link.
• Designers can also create and submit themes to Firefox Add-ons with their own header image and colors.

Tips for a better Firefox look

• Choose a dark theme at night to reduce glare, or let the System theme switch automatically.
• Pick high-contrast themes if you find tab text hard to read.
• Combine a theme with toolbar tweaks: see how to customize the Firefox toolbar.
• Themes don’t slow Firefox down noticeably, but too many extensions can. Here are tweaks to speed up Firefox.

Want more features as well as a new look? Browse our list of the best Firefox extensions.

FAQ

Do I need to restart Firefox after changing themes?

No. Themes apply instantly, just as Personas did in 2007.

Are Firefox themes free?

Themes on Firefox Add-ons are free to install.

Can I use Personas in Firefox today?

Not under that name. Personas became Firefox themes, so install themes from Firefox Add-ons instead.

Why does my theme not change the icons?

Modern Firefox themes only change colors and background images. Full icon-changing themes are no longer supported.