The 27-year-old has only played two games this year - the first was in round 10 when he returned from a broken left foot, but broke his right, and round 15 (last weekend) when he returned but reinjured his right foot.
He has re-fractured the fifth metatarsal and will have a rod removed and a screw inserted in its place.
The club says Petrie - who sustained the injury in the second term but returned to the field after half-time, despite clearly struggling - did not sustain any further damage to his foot by staying on the field in the match against the Swans.
Petrie has played 178 games for the Kangaroos since being drafted with pick 23 in the 2000 NAB AFL Draft.
