2013 In Round 4 of the
2013 NRL season, Kahu made his
NRL debut for the Brisbane Broncos against the
Melbourne Storm at centre in the 32–26 loss at
Suncorp Stadium. In the Round 9 match against the
Parramatta Eels, Kahu scored his first and second NRL tries in the Broncos 19–18 loss at
Parramatta Stadium. Soon after, Kahu extended his contract with the Broncos for 2 years, keeping him at the club until the end of the 2015 season. He scored 4 tries from 10 appearances in his debut year.
2014 Kahu injured his knee again for a third time in four years in a trial match against the
North Queensland Cowboys. In Round 19 against the
New Zealand Warriors, Kahu played his first match for the Broncos of the 2014 season playing on the wing for the suspended
Daniel Vidot and scoring a try in the 28–22 win. He finished off the
season playing in 3 matches and scoring three tries.
2015 Due to the injury of incumbent fullback
Darius Boyd during the off-season, Kahu was selected to fill in at showing promising performances in the early rounds. During a "breakout season", Kahu was rewarded with a 2-year contract extension with Broncos, to the end of the 2017 season. On 4 October, Kahu played on the wing in the Broncos' 17-16 golden point extra time loss to the
North Queensland Cowboys in the
2015 NRL Grand Final. He finished off the
2015 season having played in 22 matches, scoring 9 tries and kicking 22 goals. On 9 October, he was selected in the 23-man
New Zealand squad to tour England. Kahu was one of four members of Brisbane's Grand Final team to be included in coach Stephen Kearney's squad for the
Three-Test tour and one of six rookies to have received an international call-up by the Kiwis. On 2 November, he made his New Zealand international debut against
England, playing at centre in the Kiwis' 26–12 loss at
KC Stadium. On 14 November, in the third and final test match against
England, he scored his first international try for New Zealand in the Kiwis' 20–14 loss at
DW Stadium.
2016 On 13 February, Kahu played for the
World All Stars against the
Indigenous All Stars, playing at fullback in his team's 12–8 win at
Suncorp Stadium. In the Round 1 season opening match against the
Parramatta Eels, he scored the first try of the
2016 season in the Broncos' 17–4 win at
Parramatta Stadium. On 6 May, Kahu played for New Zealand against
Australia in the
2016 Anzac Test, playing at fullback in the 16–0 loss at
Hunter Stadium. Kahu finished the
2016 NRL season with him playing in 20 matches, scoring 15 tries and kicking 42 goals for the Broncos. On 21 September 2016, Kahu was added to the
New Zealand national rugby league team train-on squad for the
2016 Four Nations. On 3 October 2016, Kahu was selected in the final 24-man squad. Kahu played in 4 matches of tournament including starting at fullback and scoring 2 tries in the Kiwis 34-8 Four Nations Final loss against Australia at
Anfield.
2017 In February 2017, Kahu was selected in the Broncos
2017 NRL Auckland Nines squad. In Round 1 season opening match against the
Cronulla-Sutherland Sharks, Kahu put his name in the record books by scoring the first try of the 2017 season in the Broncos 26–18 win at
Shark Park, Kahu is the first player to score the first try of the season in two consecutive seasons. On 5 May 2017, Kahu played for New Zealand in the
2017 ANZAC Test against Australia where he started at centre and kicked 2 goals in the 30–12 loss at
Canberra Stadium. On 5 August 2017, Kahu extended his contract with the Broncos to the end of the 2020 season. Kahu finished the
2017 NRL season with him playing in 25 matches, scoring 9 tries and kicking 74 goals and 3 field goals for the Broncos. Kahu was in the frame to be selected in the Kiwis
2017 Rugby League World Cup squad but opted to sit out the tournament to recover from a groin injury.
2018 In Round 2 of the
2018 NRL season, Kahu fractured his jaw in the Broncos' win over the
North Queensland Cowboys. He returned 10 weeks later in the Broncos' Round 12 win over the
Parramatta Eels. He finished the 2018 season with 15 games, two tries, seven goals and 22 points, his lowest tally in all categories since 2015.
2019 On 15 February, Kahu represented the
Māori All Stars side, kicking a goal in the 14–34 loss to the
Indigenous All Stars. On 18 February, Kahu joined the
North Queensland Cowboys on a one-year deal. In Round 1 of the
2019 NRL season, he made his debut for the Cowboys, starting at fullback in their 24–12 win over the
St George Illawarra Dragons. In Round 17, he fractured his eye socket in the Cowboys' 15–12 win over the
Sydney Roosters, missing five weeks. He returned in Round 22, playing the final four games of the season. He ended the 2019 season as the Cowboys' top point scorer, with 86 points in 19 games. On 13 September, it was announced that he would be leaving the Cowboys at the end of the season. With clauses in his previous contract with the Broncos still standing, Kahu returned to the Broncos for the 2019-2020 pre-season.
2020 Hampered by the injuries and indifferent form of their available centres and wingers, Kahu made only two appearances for Brisbane in the
2020 NRL season, a year in which the club finished last on the table for the first time in their history. ==2021==