The upbeat dance track is the X Factor boyband's third UK number one single and their fourth consecutive top 10 release. The song's arrival bumps Katy Perry with 'California Gurls' and B.o.B's 'Airplanes' down a place each to second and third respectively.
Eminem & Rihanna climb the chart for the third consecutive week, advancing two paces from six to four.
As well as JLS, this week's top 10 sees two more new entries, Yolanda Be Cool and D Cup's 'We No Speak Americano' at five and 3OH!3 and Kesha's 'My First Kiss' at seven.
Kylie Minogue may have scored her fourth number one on the album chart, but her comeback single 'All The Lovers' falls six spots, from three to nine, in its fourth week on the chart.
Outside the top 10, Eliza Doolittle's 'Pack Up' is the only new entry, entering the chart at 11.
The top ten singles in full:
1. (-) JLS: 'The Club Is Alive'
2. (1) Katy Perry: 'California Gurls'
3. (2) B.o.B ft. Hayley Williams: 'Airplanes'
4. (6) Eminem & Rihanna: 'I Love The Way You Lie'
5. (-) Yolanda Be Cool & D Cup: 'We No Speak Americano'
6. (4) Enrique Iglesias ft. Pitbull: 'I Like It'
7. (-) 30H!3 ft. Ke$ha: 'My First Kiss'
8. (7) Lady GaGa: 'Alejandro'
9. (3) Kylie Minogue: 'All The Lovers'
10. (8) Example: 'Kickstarts'
> Click here for this week's albums chart