To turn on night mode in Firefox on an iPhone, open a website, tap the menu button, and tap Website Dark Mode (older versions say Turn on Website Dark Mode). Firefox flips the page to dark colors. To turn it off, open the menu again and tap the same option.
Firefox used to call this feature Night Mode; Mozilla now calls it Website Dark Mode. These steps come from three Mozilla Support articles: Website Dark Mode in Firefox for iOS, Using Dark Theme in Firefox for iOS and Change themes in Firefox for iOS. They cover both the website setting and the app’s own light and dark themes.
How to Turn On Website Dark Mode in Firefox on iPhone
- Open the Firefox app and go to any website.
- Tap the menu button. Mozilla says it is at the bottom of the screen on an iPhone and at the top-right on an iPad.
- Tap Website Dark Mode (or Turn on Website Dark Mode).
Result: the page colors switch to a dark theme. Mozilla says this can reduce eye strain in low light and may help save battery.
How to Turn It Off
Tap the menu button again and tap the same option. Mozilla says following the same steps once more reverts the display to its original theme.
Result: websites go back to their normal colors. If a page still looks dark, reload the page in Firefox on your iPhone.
Website Dark Mode vs. the Firefox App Theme
These are two separate settings:
- Website Dark Mode changes the colors of the web pages you visit.
- The app theme changes Firefox’s own menus, toolbars and tab screens to light or dark. Mozilla says Firefox matches your iPhone’s system theme by default.
So your iPhone’s Dark Mode setting affects the Firefox interface, while Website Dark Mode is the option that inverts page colors to a dark theme.
How to Change the Firefox App Theme
- Tap the menu button, then tap Settings.
- Tap Appearance. Mozilla’s older theme article calls this Theme, in the General section.
- Choose Light, Dark or Automatic.
Result: Firefox uses the theme you picked. Mozilla says Automatic can match your device’s theme or switch based on screen brightness, depending on your version.
Mozilla also notes there is a Website Dark Mode toggle on the same Appearance screen, so you can turn on dark websites from Settings instead of the menu.
Switch themes by screen brightness
According to Mozilla’s theme article, if you turn off Use System Light/Dark Mode, you can choose Automatically and set a brightness Threshold. Firefox then switches between light and dark as your screen brightness changes. Choose Manually to pick Light or Dark yourself.
Why Do Some Pages Look Odd in Dark Mode?
Mozilla says Website Dark Mode inverts the colors of a page. Pictures and logos can look strange this way. If a page is hard to read, turn the feature off for a moment.
Frequently Asked Questions
Is Night Mode the same as Website Dark Mode?
Yes. Mozilla’s help page for the feature still uses “night-mode” in its web address, but the menu option is now called Website Dark Mode.
Does Website Dark Mode save battery?
Mozilla says it can potentially save battery life, but it doesn’t promise a specific amount. Its main purpose is reducing eye strain in low-light conditions.
More Firefox iPhone Guides
- How to use private browsing in Firefox on iPhone
- How to save and find passwords in Firefox on iPhone
- How to set the home page in Firefox on iPhone
- How to hide images in Firefox on iPhone
Matthew Burleigh is the founder, head writer, and editor of Solve Your Tech, which he launched in 2012. He has written technology tutorials since 2008 and worked in IT since 2003, including small-business support, IT management, and consulting. He holds Bachelor’s and Master’s degrees in Computer Science from Arizona State University.
Matthew writes practical guides for Windows, iPhone and iPad, Microsoft Office, Outlook, Google apps, and Android. Solve Your Tech’s guides are tested on current devices or checked against official product documentation, with clear steps, sources, and update dates.
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