The 'Starships' artist's second studio album topped this week's chart by 15,000 copies.
Labrinth was beaten into second place with debut record Electronic Earth, while children's craze Moshi Monsters landed as high as this week's fourth position with Music Rox!.
Last week's number one MDNA from Madonna falls six places to seven, while Adele continues her stranglehold of the charts by climbing back into the top three with 21.
Emeli Sandé falls two spots and completes the top five with Our Version of Events.
David Guetta falls four to six with Nothing But the Beat, while Jessie J falls three to eight with Who You Are.
Lostprophets' fifth studio LP Weapons is a new entry at nine, with Orbital's latest album Wonky lands at 22.
Sean Paul's Tomahawk Technique can only manage a new placing at 34, while Ian Anderson of Jethro Tull's Thick as a Brick 2 goes in at 35.
Blur guitarist Graham Coxon's eighth studio album A+E limps into the chart at 39.
Elsewhere, Lionel Richie climbs 13 places to 26 with his country album Tuskegee, while The Script return to the top 40 with their self-titled debut album at 31.
Source: Official Charts Company
> This week's singles chart
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