The tongue-in-cheek comedy movie, which stars Channing Tatum and Jonah Hill, made over $4 million in ticket sales over the weekend, knocking last week's number one John Carter down to second place.
In third place is Nicolas Cage thriller Ghost Rider: Spirit of Vengeance, which took $827,882 at the box office. Next on the list is Project X, which tells the story of three teenagers who plan a house party that gets out of control.
Reese Witherspoon, Tom Hardy and Chris Pine's love triangle film This Means War slips from fourth to seventh place after taking $326,904 at the box office.
New entries in the list include Kevin Spacey and Stanley Tucci movie Margin Call and Johnny Depp's The Rum Diary.
The Australian box office top ten in full below (figures in Australian dollars):
(-) 21 Jump Street - $4,070,481
2. (1) John Carter - $1,575,314
3. (-) Ghost Rider: Spirit of Vengeance - $827,882
4. (2) Project X - $525,862
5. (-) Margin Call - $446,886
6. (3) Contraband - $355,782
7. (4) This Means War - $326,904
8. (-) The Rum Diary - $315,628
9. (5) The Vow - $288,797
10. (7) The Artist - $286,425
Watch a 21 Jump Street trailer below: