The track, from the singer's sophomore album 21, advances from two to one after a total of 18 weeks on the tally.
Her chart gain sees last week's frontrunner Katy Perry slip to two with 'E.T.', while Jennifer Lopez's 'On The Floor' completes the top three.
Elsewhere in the top ten, Lady Antebellum debut at seven with 'Just A Kiss', and Pitbull, Ne-Yo and Afrojack's 'Give Me Everything' jumps from 13 to eight.
Further down the chart, David Guetta lands at 14 with 'Where Them Girls At?', and Kelly Rowland's 'Motivation' reaches a new peak, leaping from 43 to 31.
Martin Solveig and Dragonette's 'Hello' vaults 76 to 62, and Jennifer Lopez's 'I'm Into You' enters at 72.
The top ten singles in full (click where possible for our reviews):
1. (2) Adele: 'Rolling In The Deep'
2. (1) Katy Perry ft. Kanye West: 'E.T.'
3. (7) Jennifer Lopez ft. Pitbull: 'On The Floor'
4. (4) Black Eyed Peas: 'Just Can't Get Enough'
5. (5) Bruno Mars: 'The Lazy Song'
6. (3) Britney Spears: 'Till The World Ends'
7. (*) Lady Antebellum: 'Just A Kiss'
8. (13) Pitbull ft. Ne-Yo, Afrojack and Nayer: 'Give Me Everything'
9. (6) Rihanna ft. Britney Spears: 'S&M'
10. (10) Chris Brown ft. Lil Wayne and Busta Rhymes: 'Look At Me Now'
Watch the video for Adele's 'Rolling in the Deep' below: