Yes, but not with the app's built-in signature. According to WiseStamp, Outlook for Android accepts only text and links there, while Microsoft Learn documents that an event-based add-in can set an HTML signature, with an image, in Outlook for Android and iOS version 4.2352.0 or later. So a company logo on every phone is a job for the add-in, not for the signature each employee types into the app.
setSignatureAsync, which Microsoft lists for Outlook on Android and iOS from version 4.2352.0. The logo has to be a JPG or PNG file, never an SVG.
Can the built-in Outlook for Android signature show a logo?
WiseStamp's guide How to add an Outlook mobile signature (updated August 25, 2026) puts it plainly: "On Android, you can't add an image but you CAN on iPhone iOS", and "Android allows only a text basic structure and links." That is the statement of a signature-tool vendor, and a competitor of ours; Microsoft Learn does not say it in as many words in the pages we checked on November 2, 2026.
Whatever the app allows, each person adds their own signature in it (Microsoft's Intune page for Outlook on iOS and Android says "Users can add their own signatures"), so it cannot guarantee a whole company the same logo and the same wording. For how the platforms compare, without repeating it here, see Outlook signatures on Mac and mobile.
How can an add-in put an HTML signature with a logo on Outlook mobile?
Microsoft's page Add-ins that run on events in Outlook on mobile devices describes the mechanism, and its list of mobile APIs shows the minimum version:
- The trigger. The
OnNewMessageComposeevent "occurs on composing a new message (includes reply, reply all, and forward), but not on editing a draft", on Outlook for Android and iOS from version 4.2352.0. - The method.
setSignatureAsyncis listed as Mailbox 1.10, for Message Compose on Android and iOS, from version 4.2352.0 or later (Outlook JavaScript APIs supported on mobile). - HTML with an image. The mobile sample on that page sets a signature with
coercionType: Office.CoercionType.Htmland adds the image as an inline attachment (addFileAttachmentFromBase64Async, referenced ascid:in the HTML). - The signature typed in the app. Learn states: "If you have a signature saved on your mobile device, it will briefly appear in the message you create, but will be immediately replaced by the signature added by the add-in."
- Limits. An add-in may run for a maximum of 60 seconds from the time it activates. For the signature itself, Learn says SVG files aren't supported in mail signatures (use JPG or PNG) and that the string is limited to 30,000 characters (Office.Body).
For how to prepare the logo file itself, see images in an Outlook signature.
What does ATOM Signatures cover on mobile?
ATOM Signatures is an event-based add-in. It covers Outlook for iOS and Android through the mobile form factor (MobileFormFactor), on Outlook version 4.2352.0 or later and for Microsoft 365 accounts. The administrator designs the signature once in the console, deploys the add-in centrally, and the signature is applied when the user composes a message, on the phone as on the computer; for the central deployment, see deploying an Outlook signature to the whole organization.
This page makes no claim about how a given signature looks on a given Android phone: rendering depends on the signature you design and on the app, and we show no screenshot of it here.
What should you check before putting a logo on every phone?
- Check the app version on a test phone: Learn lists the mobile APIs from Outlook 4.2352.0 on Android and iOS.
- Use a JPG or PNG logo, not an SVG, because Learn says SVG files aren't supported in mail signatures.
- Send yourself a message from an Android phone and from an iPhone, not only from a computer.
- Expect one quirk in replies: Learn warns that, when you select Reply from the bottom of a message, the signature is added but is not visible in the current view. Outlook signature missing or misplaced on replies covers it, with the workaround.
To see how this compares with relying on the native signature alone, read ATOM vs the native Microsoft 365 signature.
Frequently asked questions
Can Outlook for Android show a logo in the signature?
Not with the built-in signature, according to WiseStamp, which says Android allows only text and links. With an event-based add-in, yes: Microsoft Learn documents setSignatureAsync on Outlook for Android and iOS from version 4.2352.0, and its mobile sample sets an HTML signature that includes an image.
Why is the signature I typed on my phone replaced?
Because an event-based add-in replaces it. Microsoft Learn states that a signature saved on the mobile device briefly appears in the new message and is immediately replaced by the signature added by the add-in.
Which image format works in an Outlook mobile signature?
JPG or PNG. Microsoft Learn states that SVG files aren't supported in mail signatures set with setSignatureAsync, and that the signature is limited to 30,000 characters.
Does ATOM Signatures work on Outlook for Android and iOS?
Yes, for Microsoft 365 accounts. ATOM covers Outlook for iOS and Android through the mobile form factor (MobileFormFactor), on Outlook version 4.2352.0 or later.
One managed signature for every employee, on desktop and mobile. ATOM Signatures costs CA$1 per user per month, plus taxes, with a 14-day free trial.
Sources
- WiseStamp — How to add an Outlook mobile signature (Android text only, updated August 25, 2026): wisestamp.com
- Microsoft Learn — Add-ins that run on events in Outlook on mobile devices (OnNewMessageCompose, sample, 60 seconds): learn.microsoft.com
- Microsoft Learn — Outlook JavaScript APIs supported in Outlook on mobile devices (setSignatureAsync, 4.2352.0): learn.microsoft.com
- Microsoft Learn — Office.Body, setSignatureAsync (SVG, 30,000 characters): learn.microsoft.com
Sources consulted on November 2, 2026.