The Hawaii-born songwriter secured himself a rare chart double, after his debut LP Doo-Wops & Hooligans also exploded onto the album chart at pole position.
Mars becomes the first male solo artist to top both rankings since 2007, when Mika's debut album Life In Cartoon Motion joined his mega-selling single 'Grace Kelly' at number one.
This week's runner-up spot belongs to Adele and her comeback single 'Rolling In The Deep', while rap legend P Diddy and his R&B collective Diddy-Dirty Money enter at four with 'Coming Home'.
Following immediately behind are new entries in the shape of Wretch 32's 'Traktor' at five and 'Hold It Against Me', the record-breaking new release from pop icon Britney Spears, at six.
The mass of debuts in the top 10 come to an end with 'Like U Like', a collaboration between I'm A Celebrity star Aggro Santos and Girls Aloud's Kimberly Walsh, which is straight in at eight.
However, just missing out on a single digit entry is Roll Deep guest vocalist Jodie Connor, who lands at 14 with Wiley reunion 'Now Or Never'.
Meanwhile, the peak of the chart is reflected in the depths of the top 20, as Bruno Mars and Adele slip together to 18 and 19 with 'Just The Way You Are' and 'Make You Feel My Love'. Neither can replicate the crash of X Factor champion Matt Cardle, who plummets 15 places to 20 with winner's single 'When We Collide'.
The top ten in full:
1. (1) Bruno Mars: 'Grenade'
2. (-) Adele: 'Rolling In The Deep'
3. (2) Jessie J: 'Do It Like A Dude'
4. (-) Diddy-Dirty Money ft. Skylar Grey: 'Coming Home'
5. (-) Wretch 32 ft. L: 'Traktor'
6. (-) Britney Spears: 'Hold It Against Me'
7. (3) Rihanna ft. Drake: 'What's My Name?'
8. (-) Aggro Santos ft. Kimberly Walsh: 'Like U Like'
9. (4) Katy B ft. Ms. Dynamite: 'Lights On'
10. (10) JLS ft. Tinie Tempah: 'Eyes Wide Shut'
Source: Official Charts Company
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