The collective's track 'Boom Boom' tops the tally for a second week, fending off competition from Maroon 5's 'One More Night', which holds at two.
Meanwhile, Florence + the Machine's 'Spectrum (Say My Name)' leaps eight to four, Calvin Harris and Example's 'We'll Be Coming Back' bounds 11 to nine, and Justin Bieber's 'As Long As You Love Me' rounds out the top ten.
Further down the chart, Ed Sheeran shifts 12 to 11 with 'Drunk', Far*East Movement and Cover Drive's 'Turn Up The Love' vaults 31 to 16, The Wanted's 'Chasing The Sun' rises 39 to 25, and Birdy's 'People Help The People' debuts at 35.
Elsewhere, Havana Brown debuts at 40 with 'When The Lights Go Out', 50 Cent, Dr Dre and Alicia Keys start at 44 with 'New Day', and No Doubt rebound at 50 with 'Settle Down'.
The Top 10 singles in full (click where possible for our reviews):
1. (1) Justice Crew: 'Boom Boom'
2. (2) Maroon 5: 'One More Night'
3. (3) fun. 'Some Nights'
4. (8) Florence + the Machine: 'Spectrum (Say My Name)'
5. (6) Owl City ft. Carly Rae Jepsen: 'Good Time'
6. (4) Rudimental ft. John Newman: 'Feel The Love'
7. (7) Pink: 'Blow Me (One Last Kiss)'
8. (5) B.o.B ft. Taylor Swift: 'Both Of Us'
9. (11) Calvin Harris ft. Example: 'We'll Be Coming Back'
10. (10) Justin Bieber ft. Big Sean: 'As Long As You Love Me'
Watch Justice Crew's 'Boom Boom' music video below: