Mail●
Compose messages○
Signatures...→
Covers the Outlook desktop app, Outlook on the web (Microsoft 365 / Outlook.com), and the mobile app — the steps differ more than you'd expect.
Don't have a signature ready yet? Build one free in under 2 minutes.
Create a signature →Open Outlook, click File in the top left, then Options, then select Mail from the left sidebar and click the Signatures... button.
In the Signatures window, click New, give it a name, then paste your signature into the editing box below.
Edit signature
On the right side of the same window, use the Choose default signature dropdowns to assign this signature to a specific email account, and decide whether it should appear on new messages and on replies/forwards separately.
Click OK to save, then OK again to close Options.
This covers both Outlook.com and Microsoft 365's web version — the steps are identical. Click the gear icon in the top right to open Settings, then go to Mail → Compose and reply.
Paste your signature into the text box. Below it, check the boxes for Automatically include my signature on new messages and/or on messages I forward or reply to, depending on what you want.
Click Save at the bottom of the panel.
Open the Outlook app, tap your profile picture or the menu icon, then tap the gear icon for Settings.
Select the account you want to update, then tap Signature.
Toggle Use Signature on, then clear the default text and type or paste your own.
Signature looks different in Outlook than in Gmail: Outlook desktop uses Word's rendering engine rather than a standard browser engine, so modern CSS often breaks. Table-based HTML is the safest format across both.
Signature isn't syncing across devices: Outlook desktop signatures are stored locally on that computer, while Outlook web and mobile signatures are stored on the server per account. You may need to set your signature separately in each place.
Extra blank space appears above or below the signature: this is usually leftover formatting from pasting out of a word processor. Paste as plain text first, then reformat, or paste directly from an HTML signature generator instead.
Build one free — pick a template, fill in your details, and get an Outlook-ready copy button.
Create your signature →Outlook desktop renders HTML through Word's engine, which supports a narrower set of CSS than browsers do. Signatures built with table-based layouts render most consistently across both.
No — desktop signatures are stored locally on that machine, while web and mobile signatures are tied to your account on Microsoft's servers. You'll need to set it up in each place separately.
Yes — in the desktop app's Signatures window, use the account dropdown on the right to assign a specific signature to each connected account.
Outlook sometimes blocks images by default for security. Make sure the image is hosted at a public URL, and ask recipients to click "Download pictures" if their client blocks external images automatically.