The singer's collaboration with Emeli Sandé, 'Beneath Your Beautiful', spends a second week at number one, while Robbie Williams's 'Candy' debuts at two.
Rihanna is at three with 'Diamonds', Psy remains at four with 'Gangnam Style' and Adele's 'Skyfall' moves up to five.
Bruno Mars is at 14 with 'Locked Out Of Heaven', Nicki Minaj is up to 23 with 'Va Va Voom' and Wiley lands at 26 with 'Can You Hear Me? (AYAYAYA)'.
Further down the chart, Michael Jackson leaps 58 to 30 with 'Thriller', Rebecca Ferguson's 'Backtrack' slips to 33 and Calvin Harris's new collaboration with Tinie Tempah, 'Drinking From The Boittle', is at 42.
This week's Irish Top 10 is as follows:
1. (1) Labrinth ft. Emeli Sandé: 'Beneath Your Beautiful'
2. (-) Robbie Williams: 'Candy'
3. (2) Rihanna: 'Diamonds'
4. (4) Psy: 'Gangnam Style'
5. (9) Adele: 'Skyfall'
6. (3) Swedish House Mafia: 'Don't You Worry Child'
7. (5) Calvin Harris ft. Florence Welch: 'Sweet Nothing'
8. (14) Of Monsters And Men: 'Little Talks'
9. (7) One Direction: 'Live While We're Young'
10. (6) Lykke Li: 'I Follow Rivers'
Watch the music video for Labrinth and Emeli Sandé's 'Beneath Your Beautiful' below: