How to sign a PDF on iPhone: three methods that work

Signing a PDF on iPhone is quicker than most people expect. Apple's Markup tool is capable, ships with every iPhone, and works well for informal signing. For contracts and agreements where legal standing matters, the signing link method is stronger. Here are all three approaches.

Method 1: Files app Markup (quickest)

Open the PDF in the Files app. Tap the Share icon in the bottom-left corner of the screen — the box with an arrow pointing up — then tap the Markup icon (the pen-tip icon). Tap the plus button at the bottom right and select Signature. Draw your signature with your finger on the pad that appears. Tap Done, position the signature where it needs to sit in the document, tap Done again, then save.

• Open PDF in the Files app
• Tap Share icon, then the Markup pen-tip icon
• Tap + at bottom right, then Signature
• Draw with your finger, tap Done
• Drag and resize the signature to position it
• Tap Done again to save the annotated PDF

Method 2: Mail app inline signing

If the PDF arrived as an email attachment, you can sign it without leaving the Mail app. Open the email, tap and hold the PDF attachment in a reply, then tap Markup from the menu that appears. Follow the same signature steps. The signed PDF is inserted directly into your reply — quick for straightforward sign-and-return situations.

Method 3: open a signing link in Safari (legally strongest)

If someone has sent you an e-signature request, you'll receive an email with a unique signing link. Open that link in Safari. The document loads in your browser, you sign by drawing with your finger or typing your name, and the platform records the full signing event — your email address, IP address, device details, and a timestamp accurate to the second.

This method gives you a complete audit trail. The signed PDF with the Certificate of Completion goes to both parties. If the signature ever needs to be verified — in a dispute, by a solicitor, or in court — all the evidence exists in a format that satisfies ESIGN, UETA, and eIDAS requirements.

Which method should you use?

For permission slips, informal agreements between people who trust each other, or documents where you're just signing for your own records, Markup is fast and perfectly adequate. For contracts, NDAs, employment offers, or anything where someone might later dispute whether you signed or what you agreed to, use a proper e-sign platform link. The audit trail is what makes it defensible.

A note on photographing a signed document

Some people photograph a handwritten signature and call it 'signed on iPhone.' That's a photo of a signature, not an electronic signature in the legal sense. It's hard to attribute to a specific person, there's no document hash, and it's trivially reproducible by anyone with the same image. For anything that matters, sign electronically.