The singer's debut effort jumps from three to one on the tally, beating Nicki Minaj's 'Starships', which remains at two.
Meanwhile, Labrinth and Tinie Tempah's 'Earthquake' leaps from 11 to four, Justin Bieber's 'Boyfriend' enters at number five and Qwote and Pitbull's 'Throw Your Hands Up' rounds out the Top 10.
Further down the chart, Ed Sheeran leaps from 19 to 14 with 'Lego House', Timomatic debuts at 16 with 'If Looks Could Kill' and Florence + the Machine land at 19 with 'Never Let Me Go'.
T-Pain and Ne-Yo vault from 44 to 31 with 'Turn All The Lights On', and Stan Walker's 'Music Won't Break My Heart' starts at number 35.
The Top 10 singles in full (click where possible for our reviews):
1. (3) Carly Rae Jepsen: 'Call Me Maybe'
2. (2) Nicki Minaj: 'Starships'
3. (1) fun. ft. Janelle Monae: 'We Are Young'
4. (11) Labrinth ft. Tinie Tempah: 'Earthquake'
5. (*) Justin Bieber: 'Boyfriend'
6. (4) Skirllex: 'Bangarang'
7. (6) Gym Class Heroes ft. Neon Hitch: 'Ass Back Home'
8. (5) Flo Rida ft. Sia: 'Wild Ones'
9. (9) Jason Derulo: 'Fight For You'
10. (7) Qwote ft. Pitbull: 'Throw Your Hands Up'
Watch Carly Rae Jepsen's 'Call Me Maybe' music video below: