The singer's duet with Emeli Sandé, 'Beneath Your Beautiful', vaults from number 36 to the top spot following their performance on last Sunday's X Factor.
Rihanna advances to two with 'Diamonds', Swedish House Mafia are at three with 'Don't You Worry Child', Psy's 'Gangnam Style' is at four and Calvin Harris slips to five with 'Sweet Nothing'.
Naughty Boy lands at eight with his debut single 'Wonder', which features Sandé, while Adele's 'Skyfall' slides to nine.
Bruno Mars moves up to 17 with 'Locked Out of Heaven', while JLS's new single 'Hottest Girl in the World' debuts at 22.
Rebecca Ferguson climbs to 23 with 'Backtrack', Ke$ha is at 27 with 'Die Young' and Leona Lewis is at 33 with 'Trouble'.
This week's Irish Top 10 is as follows:
1. (36) Labrinth ft. Emeli Sandé: 'Beneath Your Beautiful'
2. (4) Rihanna: 'Diamonds'
3. (2) Swedish House Mafia: 'Don't You Worry Child'
4. (3) Psy: 'Gangnam Style'
5. (1) Calvin Harris ft. Florence Welch: 'Sweet Nothing'
6. (6) Lykke Li: 'I Follow Rivers'
7. (5) One Direction: 'Live While We're Young'
8. (-) Naughty Boy ft. Emeli Sandé: 'Wonder'
9. (8) Adele: 'Skyfall'
10. (7) The Script ft. will.i.am: 'Hall of Fame'
Watch the music video for Labrinth and Emeli Sandé's 'Beneath Your Beautiful' below: