How to See Deleted Notifications on Android (Dismissed Too)
Short answer: turn on Android's notification history (Settings, Notifications, Notification history) or install a notification log app. Either one saves notifications as they arrive, so a notification you swipe away can be read again. Neither can bring back notifications from before it was switched on.
Option 1: Android's built-in notification history
On Android 11 and later open Settings → Notifications → Notification history and switch it on (on Samsung: Settings → Notifications → Advanced settings → Notification history). It lists dismissed notifications from the last 24 hours. It is fine for "what was that alert a minute ago", but entries vanish after a day and there is no search.
Option 2: a notification log app
A notification log app uses Notification access to save each notification with its app, sender, text and time. Look for three things: it keeps history longer than 24 hours, it lets you search, and it stores everything on your phone instead of uploading it.
What can never be recovered
Notifications that arrived before history was on, photos and attachments, and anything the app never showed as a notification (for example a muted chat).
Doing it with Notitrail
Notitrail saves every new notification into a timeline grouped by day, by app and by conversation. Search one word, keep history 7, 30 or 90 days or forever, and tap an entry to open the original app. No subscription, no account; history stays on your phone.
FAQ
Can I see a notification I swiped away?
Yes, if notification history was on before it arrived: either Android's built-in history (Android 11+) or a notification log app.
How long does Android keep notification history?
The built-in history only keeps the last 24 hours. A notification log app can keep it for days, months or forever.
Can I recover notifications from before I turned history on?
No. Nothing records notifications retroactively, so turn history on now.
Read dismissed notifications again: get Notitrail (Google Play)