The X Factor champion's winner's single 'Impossible' retains its place at number one, while will.i.am and Britney Spears move up to two with 'Scream & Shout'.
The Lumineers slide to three with 'Ho Hey', Taylor Swift climbs to four with 'I Knew You Were Trouble' and Rihanna is up to five with 'Stay'.
David Bowie's comeback single 'Where Are We Now?' debuts at number nine, while Calvin Harris and Tinie Tempah advance to 16 with 'Drinking from the Bottle'.
David Guetta jumps to 20 with 'Just One Last Time', Imelda May is at 25 with 'Kentish Town Waltz' and Eminem's 'Lose Yourself' re-enters the Top 40 at 32.
This week's Irish Top 10 is as follows:
1. (1) James Arthur: 'Impossible'
2. (3) will.i.am ft. Britney Spears: 'Scream & Shout'
3. (2) The Lumineers: 'Ho Hey'
4. (10) Taylor Swift: 'I Knew You Were Trouble'
5. (13) Rihanna ft. Mikky Ekko: 'Stay'
6. (4) Bruno Mars: 'Locked Out of Heaven'
7. (6) Labrinth ft. Emeli Sandé: 'Beneath Your Beautiful'
8. (5) Psy: 'Gangnam Style'
9. (-) David Bowie: 'Where Are We Now?'
10. (7) Rihanna: 'Diamonds'
Watch the music video for James Arthur's 'Impossible' below: