Can you highlight a PDF on a phone?

Last reviewed: October 5, 2026 · Markdown version

Yes. On an iPhone, Apple's Preview app highlights selected text in a PDF, and Books has a marker in its Markup tools. On Android, the Google Drive app and Files by Google both have a highlighter you drag with your finger. Acrobat on mobile highlights text you select. The one choice that matters is between a highlight that follows the selected text and a freehand stroke you paint over the line, and the sections below say which each app documents.

iPhone: Preview highlights the text itself

Apple's Preview app is the iPhone route that works on the text rather than over it. Apple's page opens: "You can copy, highlight, underline, or strike through text in a PDF file." Its steps are to open the PDF, "Select and copy text, then tap Highlight", then "Choose a highlight color, or tap the underline or strike through button". A mistake is undone from the More button (Annotate a PDF or image in Preview on iPhone, iPhone User Guide, read 5 October 2026). That page's version menu lists iOS 27 and iOS 26 only, so on an older iPhone the Preview app may not be there; Books is the alternative below.

iPhone: Books and the Markup tools

For a PDF saved in Books, Apple's instruction is "Tap the page, then tap the Markup button to use the drawing and annotation tools" (Read PDF documents in the Books app on iPhone, iPhone User Guide, read 5 October 2026). Markup's highlighting is a drawing tool: you "tap the pen, marker, or pencil tool, then draw or handwrite with your finger", and Apple says you change the opacity by tapping the selected drawing tool and dragging the slider (Draw and handwrite with Markup on iPhone, iPhone User Guide, read 5 October 2026).

What about the Files app? Apple's two Files pages we read describe opening a PDF with another app or in Quick Look, and copying, moving or deleting files; neither describes marking up a PDF from Files (Find and view files and folders in Files on iPhone and Modify files and folders in Files on iPhone, iPhone User Guide, read 5 October 2026). So the documented way to highlight a PDF you keep in Files is to open it in Preview.

Android: Google Drive

Google's Drive app can mark up a PDF it is previewing. Google's page starts with a requirement, "This feature requires Android 6.0 Marshmallow or up", then: open the PDF and "At the bottom right corner, tap the annotate button." The highlighter is described as a freehand tool: "To highlight, use a wider brush tool with freehand strokes", with a choice of size and colour. When you save, Google says "You can save the original PDF or make a new copy with a new name. If you save the new copy with a new name, the original copy remains unmarked" (Annotate PDFs with a stylus or freehand on Android, Google Drive Help, read 5 October 2026). That page is written for Android only and says nothing about annotating in the Drive app on an iPhone.

Android: Files by Google

Files by Google has the same kind of tool. Open a PDF, tap Edit at the bottom right, and pick the Highlighter: "To highlight text, use freehand strokes. You can choose the highlighter size and color" (Open, manage & edit PDFs in Files by Google, Files by Google Help, read 5 October 2026). Read the saving step before you start, because the marked-up copy goes to Google Drive rather than staying on the phone; our page on Google's PDF viewers quotes it in full.

Acrobat on mobile

Adobe's mobile page gives text highlighting in one line: "Tap Highlight, Strikethrough, or Underline, then long-press and drag over the text. Tap anywhere outside the selection to apply the annotation." Tapping an existing highlight lets you change its colour or delete it (Review and annotate PDFs in Acrobat on mobile, Adobe Acrobat Help, read 5 October 2026). Adobe sets those steps inside a shared review that opens "in Acrobat on iOS"; the page does not describe the Android app or a file you have not shared, so expect the buttons to differ there.

Freehand or selected text: our advice

A highlight made by selecting text sits exactly on the words. A freehand stroke goes where your finger goes, which is fine for a paragraph and clumsy for one figure in a table. Selection needs text to select, though, and a scanned page that is only a picture may have none; how to check for a text layer takes a few seconds. On a scan, the freehand highlighters in Drive and Files by Google are the ones that will still work, because they paint over the page rather than reading it. Both points are our reading of how these tools are described, not something the vendors state.

Whichever app you use, keep the unmarked original: Drive offers to save a new copy, and a copy costs nothing. Highlighting marks what you have read; to find a word you have not read yet, search the PDF instead. For which app suits which job, see which PDF app to use.