About username changes
You can change your username to another username that is not currently in use.
Repository references
After you change your username, GitHub will automatically redirect references to your repositories.
If the new owner of your old username creates a repository with the same name as your repository, that will override the redirect entry and your redirect will stop working. Because of this possibility, we recommend you update all existing remote repository URLs after changing your username. For more information, see Managing remote repositories.
Links to your previous profile page
After changing your username, links to your previous profile page, such as https://HOSTNAME/previoususername, will return a 404 error. We recommend updating any links to your profile from elsewhere.
Accounts logged in on GitHub Mobile
Accounts logged in on the GitHub Mobile app may continue to display your original username until you log out. To ensure your updated username is displayed, we recommend you sign out and back in to your account on each mobile device.
Your Git commits
If your Git commits are associated with another email address you've added to your GitHub account, they'll continue to be attributed to you and appear in your contributions graph after you've changed your username. However, some commits using GitHub-provided email addresses may be affected. For details, see Username reference.
Your gists
After changing your username, the URLs to any public or secret gists will also change and previous links to these will return a 404 error. We recommend updating the links to these gists anywhere you may have shared them.
CODEOWNERS files
After changing your username, CODEOWNERS files that include your old username will need to be manually updated. When you view the CODEOWNERS files on GitHub, an error message is displayed if the file contains any unknown users, or users without write access. We recommend updating all relevant CODEOWNERS files with your new username.
Next steps
To change your username, see Changing your username.