The singer's debut collection 19 also returns to the number two position, after it was briefly displaced by Ryan Sheridan last week.
Kate Bush debuts at number four with Director's Cut, while Mary Byrne and Bruno Mars maintain their respective positions at five and six. Sade jumps two to number 10 with The Ultimate Collection.
As well as topping the singles chart, Jedward's debut album also enjoys a Eurovision boost as it rises 40 spots to number 12. Elsewhere, ahead of the release of Born This Way today, Lady GaGa's The Fame jumps 20 to number 17.
Also enjoying large climbs up the chart this week are the Kings of Leon, whose Come Around Sundown collection sits at number 14, Noah & The Whale's Last Night On Earth at 37 and Alexis Jordan's self-titled debut LP at 40.
Notable new entries this week come from Danger Mouse and Daniele Luppi at number 22 with Rome and Friendly Fires' Pala at 29.
1. (1) Adele: '21'
2. (3) Adele: '19'
3. (2) Ryan Sheridan: 'The Day You Live Forever'
4. (*) Kate Bush: 'Director's Cut'
5. (5) Mary Byrne: 'Mine & Yours'
6. (6) Bruno Mars: 'Doo Wops & Hooligans'
7. (4) Fleet Foxes: 'Helplessness Blues'
8. (7) Jessie J: 'Who You Are'
9. (10) Rihanna: 'Loud'
10. (12) Sade: 'The Ultimate Collection'
> Adele: 'I never planned to be a singer'
Watch Adele perform 'Set Fire To The Rain' on BBC One's The Graham Norton Show below: