The short answer
A Slack notification that won’t go away almost always points to something still unread: a thread reply, an Activity item, an app’s DM, an overdue reminder, or a second workspace you rarely open. Catch up there or mark everything as read. If the badge still sticks, reset Slack’s cache, then check the badge setting in iOS.
Why your Slack badge won’t clear
The number on Slack’s icon counts things that are waiting for you. Slack lists what can put a badge there: direct messages, keywords, mentions, app notifications, thread replies, Slack Connect invitations and overdue reminders. The badge stays until every one of them is read, wherever it lives.
Check these places, in this order:
- Threads. A reply in a thread you follow doesn’t show up in the channel itself. On iPhone, tap Threads at the top of the Home tab. Threads with unread replies sit at the top of the list.
- Activity. Its numbered badge counts unread notifications, DMs included. Open it and read what’s there, or swipe left on an item to clear it.
- DMs from apps and bots. Calendar apps, Jira and workflows send you messages too, and they count like any other DM.
- Reminders and to-dos. Overdue reminders show a badge. From October 2026 Slack is replacing Later with a To-dos tab, and to-dos with a reminder notify you in Activity. Complete or clear the overdue ones.
- Another workspace. If you’re signed in to more than one workspace, unread activity in one you rarely open may be what keeps the badge up. Switch to it and catch up, or sign out of it if you don’t need it on your phone.
How to mark all Slack messages as read
When you just want a clean slate, mark everything read in one go.
On iPhone
- Open Slack and go to the Home tab.
- Tap Catch up.
- Press and hold the Mark as Read button to mark all messages read.
On desktop
- Open the workspace with the stuck badge in the Slack desktop app.
- Press
Shift+Escto mark everything as read.
On desktop you can also open Activity and check the box at the top of the feed to select everything, then mark it all read or clear it. In the Unreads view, Mark All Messages Read sits at the bottom of the list.
Slack’s own troubleshooting page says that if badges stay after you’ve caught up, something may be out of sync on its end. That’s what the next step is for.
Reset Slack’s cache if the badge is still stuck
- In Slack on iPhone, tap your profile picture at the top of the screen, then tap Preferences.
- Under Device & Troubleshooting, tap Debug & Reset Cache.
- Tap Reset Cache.
There’s a stronger version. In the iPhone Settings app, scroll down to Slack, turn on Reset Cache on Next Launch, then open Slack. This signs you out of every workspace, so have your sign-in details ready.
If the trouble is with notifications in general, Slack has a built-in test at Profile pictureNotificationsTroubleshoot Notifications. Slack also suggests the oldest fix there is: force quit the app and restart your phone.
Clear Slack notifications on the iPhone side
Some stuck notifications belong to iOS, not Slack.
- Old banners. If a Slack alert keeps sitting on your Lock Screen or in Notification Center, swipe left on it, or on the Slack group, and tap Clear or Clear All.
- The red badge itself. If you’d rather not see a number on Slack’s icon at all, go to SettingsNotificationsSlack and turn off Badges. Notifications still arrive. The count just disappears.
- A short break. Swipe left on a Slack notification, tap Options, and mute Slack for an hour or for the day. Its notifications go straight to Notification Center with no sound or banner.
When it’s really Slack pinging you after work
Sometimes “won’t go away” means something else. You clear it at 7 PM, and by 9 PM it’s back. That isn’t a bug. It’s Slack doing its job for a team that keeps posting.
Give Slack a notification schedule and it goes quiet on its own outside your hours: tap your profile picture, then Notifications, then Allow notifications under Notification schedule, and choose Weekdays or Custom. The full walkthrough is in how to stop Slack notifications after work. If a pause starts behaving oddly, see how to turn off pause notifications in Slack, and to cut daytime noise too, work through this checklist to reduce Slack notifications.
A schedule stops Slack reaching out. The badge is a quieter nudge: it waits on your Home Screen for you to tap it. If the evening tap is the habit, the fix is keeping the app itself shut after hours.
Questions
Why does Slack show a badge when I have no unread messages?
Usually there’s an unread thread reply, an Activity item, a DM from an app, an overdue reminder, or unread activity in another workspace. If you’ve checked all of those, mark everything as read and reset Slack’s cache.
How do I mark all Slack messages as read on iPhone?
From the Home tab, tap Catch up, then press and hold the Mark as Read button. On desktop, press Shift and Esc together in the workspace.
How do I get rid of the red dot on Slack on my iPhone?
Go to Settings, then Notifications, then Slack, and turn off Badges. This hides the count without changing your Slack notifications.
Why do Slack notifications keep coming back after I clear them?
New messages create new notifications. Set a notification schedule in Slack so notifications pause outside your working hours.
Sources
Menu names change between app and iOS versions. These are the official pages, checked October 9, 2026.