Sign a PDF on an iPhone
An iPhone can fill out and sign a PDF without another app: the Files app adds your signature to a document, and Markup does the same for a PDF attached to an email.
With the Files app
- Open the PDF on your iPhone. If asked, open it in the Files app and tap Save.
- To fill in fields, tap the AutoFill button, tap a blank field and type.
- Tap the Add button, tap Add Signature, sign with your finger, then tap Done. Drag the signature to where it belongs.
- When you're done, tap the Menu button, then Export, Print or Share to send the signed document.
Source: Fill out forms, sign documents, and create signatures on iPhone (Apple Support, checked 13 Nov 2026)
In Mail, with Markup
- In a new email or a reply, tap inside the message, tap the Attachment button, then the Document button, and choose the PDF.
- Tap the attachment, then the gray arrow, then the Markup button.
- Tap the plus button to add your signature.
- Tap the More button, tap Done, then send the email.
Source: Use Markup on your iPhone, iPad, or iPod touch (Apple Support, checked 13 Nov 2026)