The 'Rolling In The Deep' singer once again outperformed Beyoncé's 4 and her own debut LP 19 to capture the title.
Caro Emerald takes her Deleted Scenes From The Cutting Room Floor to a new peak of four after climbing two more places, while Lady GaGa rounds out the top five with Born This Way.
This is the second all-female top five to occur this year, after Adele's albums, Katy B's On A Mission, Rihanna's Loud and Who You Are by Jessie J secured the top spots back in April. Female artists have spent a combined total of six months at number one on the album chart in 2011, while male artists have held pole position for just four weeks.
Elsewhere, Rihanna's aforementioned LP clambers three places to seven, where it is followed by a new entry from LMFAO entitled Sorry For Party Rocking at eight and Chase & Status's No More Idols, up two to nine.
Take That, meanwhile, tumble out of the Top 10 after falling three places to 12 with Progress, as Chris Brown's comeback album F.A.M.E. climbs another four entries to 14.
Further down, The Horrors find themselves lingering at 17 after an impressive debut at five last Sunday with Skying, while The Script's September 2010 release Science & Faith launches 14 spots to 18 in its 45th week on the chart.
The dramatic contrasts continue at the depths of the top 20, as Katy Perry's Teenage Dream bounces to 19 from 22 off the back of her MTV VMA nominations, Arctic Monkeys' former chart-topper Suck It And See crashes five to 20 and Elbow's Build A Rocket Boys! blasts to 21 from last week's 34.
The Top 10 in full:
1. (1) Adele: '21'
2. (2) Beyoncé: '4'
3. (3) Adele: '19'
4. (6) Caro Emerald: 'Deleted Scenes From The Cutting Room Floor'
5. (4) Lady GaGa: 'Born This Way'
6. (7) Bruno Mars: 'Doo Wops & Hooligans'
7. (10) Rihanna: 'Loud'
8. (-) LMFAO: 'Sorry For Party Rocking'
9. (11) Chase & Status: 'No More Idols'
10. (8) Foo Fighters: 'Wasting Light'
Source:Official Charts Company
> This week's singles chart
Watch Adele perform 'Don't You Remember' from her number one album 21 below:
View the latest Official Top 100 Album Chart