The group climbed from two to one on the tally, fending off competition from Flo Rida and Sia's 'Wild Ones', which leaps 24 to two, while Coldplay's 'Paradise' completes the top three.
Meanwhile, Timomatic's 'Set It Off' leaps from 12 to four, while Reece Mastin slips from five to ten with 'Good Night'.
Further down the chart, Simple Plan lift 22 to 11 with 'Summer Paradise', Christina Perri's 'A Thousand Years' jumps 19 to 15, and Laurent Wery's 'Hey Hey Hey' advances 32 to 23.
The Black Keys rise 44 with 32 to 'The Lonely Boy', 360 and Gossling re-enter at 35 with 'Boys Like You', and Skrillex start at 44 with 'Bangarang'.
The Top 10 singles in full (click where possible for our reviews):
1. (2) Foster The People: 'Pumped Up Kicks'
2. (24) Flo Rida ft. Sia: 'Wild Ones'
3. (3) Coldplay: 'Paradise'
4. (12) Timomatic: 'Set It Off'
5. (4) Snoop Dogg ft. Wiz Khalifa and Bruno Mars: 'Young, Wild & Free'
6. (1) LMFAO: 'Sexy And I Know It'
7. (7) Guy Sebastian: 'Don't Worry Be Happy'
8. (8) One Direction: 'What Makes You Beautiful'
9. (9) Flo Rida: 'Good Feeling'
10. (5) Reece Mastin: 'Good Night'
Watch the 'Pumped Up Kicks' music video below: