Leilua previously played for the Sydney Roosters, Newcastle Knights and the Canberra Raiders in the National Rugby League.

He was then placed on a one-year good behaviour bond after being found guilty of sending nude photos of his former girlfriend to her brother and a friend.

[26][27] In round 26 against the St George Illawarra Dragons, Leilua played his 100th NRL career match, scoring a try in Newcastle's 40–10 win at Hunter Stadium.

In the pre-season, Leilua was reportedly on the outer with new Knights coach Rick Stone, after he returned to training overweight and was rumoured to have had a run-in with the senior Newcastle player Beau Scott about his attitude and fitness.

[43] During the season, Leilua and his wing partner Jordan Rapana became one of the most destructive duos of year, scoring and setting up some fantastic tries and their strong friendship outside the footy field labelling them as "Leipana".

[47][48] On 28 September 2016, Leilua was named as the Centre of the Year at the 2016 Dally M Awards night, a significant uprise from being in the lows of falling out of favour at the Newcastle Knights at the start of 2015 NRL season.

In round 6 against the Gold Coast Titans, Leilua played his 150th NRL career match and scored a try in the 42–16 win at Robina Stadium.

[56][57] At the end of the season, there was rumours that Leilua was set to be forced out of Canberra to join the Gold Coast Titans to ease their salary cap after a hot-and-cold mixed form year.

[58] After playing in the World Cup, Leilua along with Samoan representative team-mates Josh Papalii and Junior Paulo were confronted by coach Ricky Stuart after they arrived at pre-season training overweight, the trio were forced to join the dreaded "Fat Club", doing extra cardio training sessions to get back into a respectable weight.

"This is Josh and Brett Morris, who have done everything in the game and achieved a whole lot more than BJ looks like he will," "You don't disrespect those kinds of players in those situations where you've been poor yourself up until that moment.

"[60] On 26 September 2018, Leilua was a shock winner of the Centre of the Year award after beaten clear favourite, the Sydney Roosters boom youngster Latrell Mitchell.

Leilua began the 2019 NRL season in good form scoring 4 tries in 7 games as the club sat in the top 4 of the competition in the opening rounds.

[62][63] In round 22, Leilua would make a shock early return to play his 200th game in Canberra's 18–22 win over the Melbourne Storm at AAMI Park.

Leilua played at centre in the 2019 NRL Grand Final as Canberra were defeated 14–8 by the Sydney Roosters at ANZ Stadium.

[70] Leilua played a total of 14 games for Wests in the 2020 NRL season scoring four tries as the club finished 11th and missed out on the finals.

[73] On 20 October, Leilua took to Instagram and denied media reports that he had signed a train and trial contract with the Wests Tigers worth $1000 a week.

Leilua also attacked Wests head coach Michael Maguire writing “Btw I wouldn’t play for someone that blames the team all the time!

[75] On 22 December, Leilua made his boxing debut against former NRL player Chris Heighington in the Footy Fight Night Christmas Bash.

After being declared the winner, Leilua went on a foul mouthed tirade in the post-match interview saying “For all those haters that f***ing said I can’t last four rounds, thanks mate, “You gave me the inspiration tonight.

[78] Following his exit from Featherstone Rovers at the end of the 2023 season, on 8 November it was reported that he was heading back to Australia to resume his boxing career.