How to Sign a PDF on iPhone (Every Method)

A form lands in your inbox, it needs signing, and the nearest computer is somewhere else. There are four realistic ways to handle that on an iPhone, and they are genuinely different — the right one depends on whether the PDF has real form fields, whether you need to type as well as sign, and whether you will ever need the same signature again.

1. Markup, for a signature and nothing else

iOS has signing built in. Open the PDF in Files or Mail, tap the Markup icon (the pen tip in a circle), tap the plus button, and choose Signature. You can draw one with a finger, or with an Apple Pencil on iPad, and iOS keeps it for next time.

This is the fastest route and it costs nothing, so it should genuinely be your first try. Its limit shows up the moment the form needs more than a signature: Markup gives you a text box, but placing and sizing text across twelve fields is slow and the result usually looks it.

2. Mail, when the PDF arrived as an attachment

If the document came by email, long-press the attachment in Mail and choose Markup. You get the same tools without the file ever leaving the message, and replying sends the signed version back. For a one-page agreement that needs a signature and a date, this is the shortest path there is.

3. Files, when you need to keep the signed copy

Saving the PDF into Files first is worth the extra step whenever the signed document matters later — a lease, a contract, anything you may be asked to produce again. Mark it up in place and the signed version replaces the original in iCloud Drive, where it is backed up and searchable.

4. A dedicated app, when the form is actually a form

The case Markup handles badly is the common one: a scanned form with twenty boxes, no real PDF form fields, and a deadline. You need to type into arbitrary positions, keep the text aligned, tick boxes, add a date, and sign — and you need it to look like it was filled in properly rather than annotated.

That is what a dedicated filler is for. Sign Any PDF places text anywhere on the page whether or not the PDF has fields, keeps a saved signature, and shares the finished file straight back to Mail, Messages or Files.

Which one to use

• One signature, nothing else, arrived by email — Markup in Mail.
• One signature, and you need to keep the file — save to Files, then Markup.
• A scanned form with several fields to fill — a dedicated filler.
• Something you will sign repeatedly, like weekly timesheets — a dedicated filler with a saved signature.

Is a signature drawn on a phone legally valid?

In most jurisdictions an electronic signature is valid for ordinary agreements, and a drawn signature on a PDF is a common form of one. Certain documents — wills, some property transfers, some court filings — are exceptions and may require a wet signature or a witness. If the document says how it must be signed, follow that; if a lot turns on it, take advice rather than a blog's word.