In 2012 and 2013, Brown played for the Wests Tigers' NYC team. On 30 September 2012, he played in the Tigers' 2012 NYC Grand Final win over the Canberra Raiders. On 18 July 2013, he re-signed with the Tigers on a 3-year contract.
2013
In Round 24 of the 2013 NRL season, Brown made his NRL debut for the Wests Tigers against St. George Illawarra. As Wests Tigers had exceeded their second-tier salary cap, the NRL had to grant a special dispensation for Brown to play as neither team could reach the semi-finals. However, Brown was precluded from playing in any further games for the season.
2015
On 2 March, Brown signed a 2-year contract with South Sydney effective immediately, after being released from his Wests contract. He made his South Sydney debut in round 6 of the 2015 NRL season against North Queensland. He finished off the year with seven games for Souths, starting in the second-row on two occasions.
2016
Brown was a regular in first grade in 2016, playing prop or lock. In round 13 he avoided suspension after attempting to kick a player in the groin. The next week, he was described as, "one of rugby league’s dirtiest players, biggest thug and throwback to the old days," after a late shot on Mitchell Moses. Coach Michael Maguire said, "Seriously I think he’s a good kid but he’s playing on the edge when fatigue sets in. He’s got to be more aware of those moments in the game." In September, Brown signed a 2-year contract with the Parramatta Eels starting in 2017.
2017
After a stellar first season with Parramatta, Brown was awarded the Ken Thornett Medal for being Parramatta's best player in 2017. Brown was named in the Italy training squad for the 2017 world cup. Brown played in all three of Italy's pool matches at the world cup including the 46-0 demolition of The United States.
2018
On 6 March 2018, Brown signed a new contract to stay at Parramatta until the end of the 2020 NRL season. In Round 5 against Penrith, Brown suffered an ankle injury in the 12-6 loss and was ruled out indefinitely. On 2 June 2018, Brown made his long-awaited return from injury in Parramatta's 30-4 defeat by Newcastle. Brown made a total of 15 appearances for Parramatta as the club endured a horrid season finishing last on the table and claimed its 14th wooden spoon.
2019
In round 1 2019 against the Penrith Panthers, Brown was taken from the field during the first half after damaging his left pectoral muscle. It was later revealed that Brown would be ruled out for 3 months. Brown made his return to the Parramatta side against Cronulla-Sutherland in Round 13 which ended in a 42-22 loss at Shark Park. In Round 23 against arch rivals Canterbury-Bankstown, Brown was placed on report and sent to sin bin after hitting Canterbury player Dallin Watene-Zelezniak with an illegal shoulder charge. Parramatta would go on to lose the match 12-6 in a shock loss at the new Western Sydney Stadium. with Brown receiving a two match suspension. On 7 October, he was named in the Australian side for the 2019 Rugby League World Cup 9s.
2020
Brown picked up an option in his current contract with Parramatta, keeping him at the club til then end of the 2021 season.
