How to Underline Text on iPhone (Every App: Notes, Mail, Messages, Safari & More)

iPhone makes underlining text easy in some apps and almost impossible in others. Apple's built-in apps — Notes, Mail, Pages, Reminders — all support rich text formatting natively, with a clean menu for bold/italic/underline. But the moment you switch to Instagram, WhatsApp, Twitter, or any third-party social app, those formatting buttons disappear.

This guide covers every method, app by app, with the exact taps and screens. Plus a Unicode workaround for the apps that don't support underline at all.

The two approaches on iPhone

There are two completely different ways to underline text on iPhone:

1. Rich text underline (HTML-style) — works in Apple's own apps and a few others. The text is genuinely formatted; you can change the font, color, etc.
2. Unicode underline — works anywhere you can paste text. Each character is a normal letter plus a combining underline mark, so it travels with you.

For Apple apps, use rich text. For social media and chat apps, use Unicode. We'll cover both.

Apple Notes (rich text underline)

The Notes app supports full rich-text formatting:

1. Open the Notes app
2. Create a new note or open an existing one
3. Type your text
4. Tap and hold the text you want to underline → tap Select or use the magnifying loupe to highlight the exact words
5. From the floating menu, tap the Aa button (or the underlined "B" formatting icon — depending on iOS version)
6. Tap Underline in the formatting menu

Alternative: If the formatting toolbar is visible at the top of the keyboard, tap the Aa icon there → choose Underline.

To remove an underline, select the text and tap Underline again.

💡 Tip: Notes also lets you set default formatting for new notes. Settings → Notes → "New Notes Start With" → Body / Heading / etc. This won't add underline by default, but it controls baseline styling.

iMessage / Messages

This is where many people get stuck. iMessage doesn't have a native underline button. Apple's official Messages app supports basic emphasis (bold, italic, strikethrough) only via a relatively recent feature called Text Effects in iOS 18+.

Native method (iOS 18 and later)

1. Type your message in the iMessage text field
2. Tap and hold a word → Select the word(s)
3. From the format menu that appears, tap Aa
4. Choose from: Bold, Italic, Underline, ~~Strikethrough~~

If you don't see the Aa option, your iOS version is older than 18. In that case, use the Unicode method below.

Unicode method (any iOS version)

Works on every version of iMessage going back to iOS 9, and works equally on Android recipients (via SMS/RCS):

1. Open Safari and go to Underline Text Generator
2. Type your text and pick a style
3. Tap the copy button
4. Switch to Messages, tap and hold in the input field, choose Paste
5. Send

The recipient sees underlined text regardless of their device or OS version.

Mail (Apple Mail app)

Apple Mail supports rich text formatting in compose mode:

1. Open the Mail app and tap Compose (square + pencil icon, top right)
2. Tap into the message body and type your text
3. Tap and hold the text to select it
4. In the floating menu, tap the right arrow → BIU (Bold/Italic/Underline)
5. Tap Underline

Alternatively, with text selected, tap < above the keyboard until you see the format options, then tap Underline.

The underline travels with the email — it's HTML formatting, so any modern email client (Gmail, Outlook, Yahoo, etc.) will display it correctly on the recipient's end.

Safari (web pages and forms)

Underlining text in Safari depends on what you're trying to underline:

Underline in a webpage form (e.g., a contact form, comment box)

Most web forms use plain text inputs that don't support rich text. To underline text in those, use the Unicode underline method — generate, copy, paste.

Underline in Safari's built-in note features (Reading List notes, share extension)

When you share a webpage to Notes via Safari's Share menu, you can underline annotations using Notes' rich text method described above.

Underline in a textarea on a website you control

If you're editing a webpage where rich text editing is enabled (like a CMS, Google Docs in Safari, or a forum with a WYSIWYG editor), select the text → tap the underline icon in that site's editor. The site's CMS handles the formatting, not Safari itself.

Pages (Apple's word processor)

Pages has the most powerful native formatting on iPhone:

1. Open Pages and create or open a document
2. Type your text
3. Select the text by tapping and holding, then dragging the selection handles
4. Tap the paintbrush icon at the top of the screen
5. In the Style tab, tap Underline (it appears as U with a line below it, alongside B and I)

Pages also supports advanced underline options like double underline, dotted underline, and underline color. Tap the dropdown next to Underline to access these.

Reminders

Apple's Reminders app added rich text support in iOS 15. To underline:

1. Open a reminder list or create a new reminder
2. Tap into the Notes field below the reminder title (the title itself is plain text)
3. Use the rich text toolbar above the keyboard → Aa → Underline

The reminder title cannot be underlined natively. For that, paste in Unicode underlined text.

Instagram, WhatsApp, Twitter, TikTok, Discord, Snapchat (Unicode method)

None of these apps support native underline on iPhone. The workaround is Unicode underline, which works in all of them.

The universal process:

1. Open Safari → go to Underline Text Generator
2. Type your text, pick a style, tap copy
3. Open the destination app (Instagram, WhatsApp, etc.)
4. Tap and hold the input field → Paste
5. Send/post

Specific guides:

• Instagram: see our full Instagram guide
• WhatsApp: see our WhatsApp guide
• Discord: see our Discord guide — Discord also supports native markdown underline using __double underscores__

💡 Pro tip: Add the Underline Text Generator to your iPhone home screen for instant access. Open it in Safari, tap the Share button, then tap Add to Home Screen. Now it opens like an app whenever you need styled text.

How to use iPhone shortcuts for faster underlining

If you frequently underline the same word or phrase, iPhone Shortcuts can save you serious time.

Setting up an "Underline" shortcut:

1. Open the Shortcuts app
2. Tap + to create a new shortcut
3. Add the action Get Text from Input (set "Allow" to Text)
4. Add Replace Text actions to swap regular letters with their U+0332 versions (or use a generic "transform text" action if you want)
5. Add Copy to Clipboard as the final action
6. Save the shortcut and add it to your home screen

This is admittedly more setup than just using our generator, but it's useful if you underline text dozens of times per day.

For a faster path: use the Share Sheet approach. Many text utility apps from the App Store add an "Underline" option to your share sheet — but always check reviews to ensure they don't track your text.

Underlining text in third-party Apple-style apps (Bear, Day One, Things, Drafts)

Many popular productivity apps on iPhone use rich text formatting like Notes:

• Bear: Select text → tap underline icon in formatting bar (Bear uses a custom Markdown-like underline syntax: ~text~ underlines in some themes)
• Day One: Select text → tap B/I/U in the formatting toolbar above the keyboard
• Drafts: Markdown-based; no native underline, use Unicode
• Things: Doesn't support text formatting; use Unicode in notes
• Ulysses: Markdown-based; supports ~~strikethrough~~ and others, no underline

When in doubt, look for a Aa or B I U button when text is selected. If it's not there, the app doesn't support rich underline natively.

Underlining text in Google apps on iPhone (Docs, Gmail, Keep)

Google's iOS apps mostly support rich text:

• Google Docs (iPhone): Select text → tap A with paintbrush icon → Underline toggle
• Gmail (iPhone): Tap the A formatting icon at the top of the compose screen → tap Underline (U)
• Google Keep (iPhone): Tap the + in a note → tap B I U → tap Underline

These all use HTML formatting, so the underline travels with the document/email.

When iPhone's underline doesn't carry across

Sometimes you underline text in one app and copy it to another, only to find the underline is gone. Common cases:

| You copied from… | …and pasted into… | Likely result | |---|---|---| | Notes (rich text) | iMessage | Plain text — underline lost | | Mail (rich text) | iMessage | Plain text — underline lost | | Pages (rich text) | Instagram bio | Plain text — underline lost | | Notes (rich text) | Pages | ✅ Underline preserved | | Notes (rich text) | Mail | ✅ Underline preserved | | Underline Generator (Unicode) | Anywhere | ✅ Underline preserved |

The pattern: Rich text underlines only travel between apps that both support rich text. Unicode underlines work everywhere.

Frequently asked questions

Why doesn't iPhone have a single universal underline button?

Because iPhone supports two different text systems: rich text (used in Apple apps and email) and plain text (used in chat, web forms, social media). A "universal" button would require Apple to standardize how Unicode formatting is applied — which is a non-trivial design decision. For now, you have to use the right method for the right app.

Can I set up a keyboard shortcut for underline on iPhone?

Yes, partially. iPhone supports Text Replacement (Settings → General → Keyboard → Text Replacement), where you can set a short trigger phrase to expand into a longer text. You can pre-generate underlined Unicode words in our tool and save them as text replacements — for example, type ;ig and have iPhone replace it with M̲y̲ ̲I̲n̲s̲t̲a̲g̲r̲a̲m̲.

Does Siri's dictation support underline?

No. Siri dictation outputs plain text without formatting. You'd dictate the text first, then apply underline manually using one of the methods above.

Will my underlined text look the same on the recipient's iPhone?

If you used rich text (Notes, Mail, Pages): yes, as long as the recipient's app also supports rich text.

If you used Unicode underline: yes — Unicode is part of the text itself, so it renders identically on iPhone, iPad, Mac, Android, and Windows. (Very old devices may show small visual glitches; see our troubleshooting guide.)

Can I underline a single emoji?

No — emojis don't accept combining marks reliably. The underline either floats in space, doesn't appear, or breaks the emoji rendering.

Why does my underlined Unicode text get auto-corrected?

iPhone's keyboard auto-correction can mangle underlined Unicode. To avoid this: paste underlined text last, after typing the rest of your message, or temporarily disable auto-correction in Settings → General → Keyboard → Auto-Correction.

Can shortcuts apps like Carrot or Drafts underline text on iPhone?

Drafts has a workspace called Markdown actions that includes a custom underline transform you can wire up. Several App Store text utilities advertise underline as a feature — they're usually using the same Unicode method our generator does, just bundled into a different UI.

Underline anything on your iPhone in 30 seconds

For Apple's own apps, use the native Aa → Underline button. For everything else — Instagram, WhatsApp, Twitter, Discord, TikTok — use Underline Text Generator directly in Safari. Add it to your home screen and underlining anywhere becomes a 30-second task.

For more iPhone text tricks, check out our fonts generator — bold, italic, script, and 100+ Unicode styles that work in any iPhone app.