Former rugby league star Anthony Mundine stopped New Zealand's Gerrard Zohs in his first professional boxing fight in Sydney on Monday.

Mundine, formerly a stand-off for the St.George-Illawarra Dragons, floored his opponent in the first and fourth round before referee Billy Males brought an end to the contest.

During the build-up to the contest, Zohs had attracted interest by stating that Mundine would not be able to withstand the power of his punches.

But fighting in front of 7,428 spectators and a host of celebrities, the 25-year-old Mundine, fighting at Sydney, was in total control of the contest, admittedly against an opponent with a record of ten wins and now ten defeats.

The winner turned to boxing after walking out on the Dragons earlier this year, citing entrenched racism as one of the reasons.

Mundine's father Tony was a professional boxer who competed at middleweight.