The Britain's Got Talent veteran outperformed a climbing Michael Bublé and his Christmas record to snatch the top spot from Florence + the Machine, who are are at three this week with Ceremonials.
New entries Sticks + Stones by Cher Lloyd and Battleground by The Wanted complete the top five, Coldplay slip four to six with Mylo Xyloto and Dutch conductor André Rieu debuts at seven with his Johann Strauss Orchestra record And The Waltz Goes On.
Alfie Boe slips out of the Top 10 after one week with Alfie, which is down six to 12, while the new entries continue with Birdy's self-titled debut album at 13, Pink Floyd best-of collection A Foot In The Door at 14 and Simon & Garfunkel's Greatest Hits at 16. Professor Green's At Your Inconvenience nestles in between the latter two new entries at 15 after dropping from last week's three.
Also slipping are Matt Cardle and Rizzle Kicks, who grab the last spots in the Top 20 by falling seven and 11 respectively with Letters and Stereo Typical.
Adele's 19, meanwhile, leaves the upper half of the chart for the first time since its successor 21 arrived in January by slipping two to 21. Kelly Clarkson also misses the bestsellers with Stronger, which is down eight to 22, and Diana Ross returns to the rankings with The Greatest, a new entry at 24.
The Top 10 in full:
1. (-) Susan Boyle: 'Someone To Watch Over Me'
2. (5) Michael Bublé: 'Christmas'
3. (1) Florence + the Machine: 'Ceremonials'
4. (-) Cher Lloyd: 'Sticks + Stones'
5. (-) The Wanted: 'Battleground'
6. (2) Coldplay: 'Mylo Xyloto'
7. (-) André Rieu & His Johann Strauss Orchestra: 'And The Waltz Goes On'
8. (4) Noel Gallagher's High Flying Birds: 'Noel Gallagher's High Flying Birds'
9. (7) Adele: '21'
10. (8) Ed Sheeran: '+'
Source: Official Charts Company
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Listen to 'Unchained Melody' from Susan Boyle's number one album Someone To Watch Over Me below:
View the latest Official Top 100 Album Chart