macOS lets you designate a single default browser that opens when you click links in email, messages, or other apps, and Firefox can be set as that browser. This guide explains how to change default settings at the system level, verify protocol handlers for http and https, and keep Firefox up to date so links reliably open as expected. You will also see how to review and reset handlers if another app has taken over. Follow these evergreen steps to ensure macOS routes web links through Firefox by default.
Check the Current Default Browser
Before changing settings, confirm which app macOS currently designates as default for web links. Open System Settings (or System Preferences on older macOS), click General, then check Default web browser. If it already says Firefox, no further action is needed. If another browser appears, you are ready to switch. Note the current setting so you can compare after changes.
Set Firefox as the Default Browser in System Settings
macOS controls default browser behavior in a single location. Changing this updates the default protocol client for http and https links across the system.
Open General Preferences
Choose Apple menu > System Settings > General (or System Preferences > General). Locate Default web browser and select Firefox from the list. This is the primary step to make Firefox the systemwide default.
Verify or Reset Handlers for http and https
Some apps register custom protocol handlers that can override the default browser setting. To review or reset these:
- Open System Settings > Privacy & Security > Default web browser.
- Scroll to the bottom of the list to review apps that register URL handlers.
- If an app should not handle web links, select it and click Remove or Reset.
After removing unwanted handlers, relaunch Firefox and allow it to register as the handler for http and https when prompted.
Configure Firefox to Register as the Default Handler
Firefox must register itself as the handler for http and https URLs. On first launch, macOS usually prompts to use Firefox as default; accept this. If you missed the prompt, you can re-trigger it:
- Open Firefox.
- Type about:config in the address bar and press Enter (accept the risk warning if shown).
- Search for the preference browser.safari.app.browserPrefix (or similar handler entries) if present, but on macOS the standard method is the system prompt or the Default web browser setting described earlier.
Firefox will request to handle links when first set as default or when you explicitly choose it in System Settings. Ensure no error messages appear during registration; otherwise relaunch Firefox and try again.
Verify Protocol Associations per App
Individual apps sometimes store their own choice of browser for specific actions. Email, messaging, and productivity apps may open links in their internal viewers or a configured browser. Check app preferences and set Firefox explicitly when options are available.
Email and Messaging Clients
- Mail: In Mail > Preferences > General, set Opening links to Firefox.
- Messages: In Messages > Preferences, set Web links to Firefox if the option exists.
- Other apps: Consult the app documentation for browser selection, and choose Firefox as the external browser.
Troubleshoot When Links Do Not Open in Firefox
If links still open in another app after setting Firefox as default, one of these issues may be present:
- Another app registered a more specific URL handler.
- Firefox did not successfully register as the default handler.
- Settings within individual apps override the system default.
Use this diagnostic flow to resolve common causes.
Check and Reset Default Web Browser Entries
Review the list of apps with URL handlers in System Settings > Privacy & Security > Default web browser. Remove entries for browsers you do not want as default, or for apps that should not handle web links. After removal, relaunch Firefox and allow it to register again.
Relaunch Firefox and Reaccept Prompts
Quit Firefox completely (Cmd-Q), then reopen it. macOS may show a prompt asking which app to use for web links; choose Firefox and select Always if offered. If no prompt appears, manually set Firefox in System Settings > General > Default web browser.
Clear Cached Handlers in the Terminal (Advanced)
In rare cases, cached handler data can persist. Open Terminal and run the following commands cautiously:
- lsregister -kill -r -domain local -domain system -domain user
- lsregister -kill -r -domain com.apple.LaunchServices
These commands ask Launch Services to forget cached app associations. After running them, restart your Mac and reopen Firefox to re-register as the default.
Maintain Default Browser Status
Default browser settings can change after app updates or reinstalls. Periodically verify System Settings > General > Default web browser to confirm Firefox remains selected. If you notice changes, repeat the steps above. Routine checks ensure consistent behavior for opening links across macOS.
Quick Reference: Steps at a Glance
- Open System Settings > General and select Firefox from Default web browser.
- Review Default web browser entries under Privacy & Security and remove unwanted handlers.
- Allow Firefox to register as handler for http and https when prompted, or reaccept in Firefox after changing settings.
- Check individual apps (Mail, Messages, etc.) and set Firefox as their external browser where possible.
- If needed, relaunch Firefox, restart your Mac, and clear Launch Services caches to fix stubborn conflicts.
Summary
Making Firefox the default browser on macOS involves changing the Default web browser setting in System Settings, removing conflicting URL handlers, and ensuring Firefox can register to handle http and https links. Verify per-app settings in Mail and other apps, troubleshoot with handler checks and Terminal commands if needed, and periodically confirm the default remains set. With these evergreen steps, links on your Mac will consistently open in Firefox.