Cook grew up in his home town of Helensburgh, New South Wales, in the Illawarra region of Australia. He was a state champion in the NSW Surf Life Saving Championships throughout his youth.[citation needed]
On 27 September, Cook was named on the interchange bench in the 2015 New South Wales Cup Team of the Year, for a second year.[13] On 15 October, Cook signed a 2-year contract with the South Sydney Rabbitohs starting in 2016.[14][15] Cook played a total of 37 reserve grade games for Canterbury and scored two tries.[16]
On 6 March 2016, Cook made his debut for Souths against the Sydney Roosters and scored a try in Souths 42–10 win. Cook went on to play a further 17 times for the 2016 NRL season. Cook also featured for Norths in The NSW Cup making two appearances.[18][16]
On 1 May 2017, Cook was named in The NSW Country Origin representative team to play against The NSW City representative side in the last ever City vs Country game.[20]
2018
Cook started the 2018 NRL season as the first choice hooker for Souths over Robbie Farah. This year was Cook's most successful year. He made his debut for NSW in state of origin and the Australian Kangaroos. On 28 May 2018, Cook was selected to play for NSW against Queensland in the 2018 State of Origin series after a number of good performances at club level.[21] Cook played in all 3 games for New South Wales as they won their first origin series since 2014.[22]
Cook was part of the Souths side which finished 3rd on the table at the end of the regular season and made it all the way to the preliminary final before being defeated by arch rivals the Sydney Roosters 12–4.[23]
He capped a stellar season by earning selection in the Australian Kangaroos team as starting hooker for Test matches against New Zealand and Tonga.[24]
On 5 December Cook signed a five-year deal worth $4.5 million to stay with Souths until the end of 2023.[25]
2019
After a good start to the 2019 NRL season for Souths, Cook was selected to play for New South Wales in the 2019 State of Origin series. In the series decider at ANZ Stadium, Cook scored a brilliant individual try as New South Wales defeated Queensland 26-20 winning their second series in a row. The match was won in the last 20 seconds courtesy of a try scored by James Tedesco.[26][27]
Cook made a total of 26 appearances for Souths in the 2019 NRL season as the club finished third on the table and qualified for the finals. Cook played in all three of the club's finals games as they reached the preliminary final against the Canberra Raiders. Cook had a game to forget in the preliminary final which culminated when he missed a one on one tackle with Canberra forward Josh Papalii who scored under the posts to win the match 16–10.[28][29][30][31] On 7 October, Cook was named in the Australian side for the Oceania Cup fixtures.
2020
In round 10, Cook scored two tries as Souths lost the match 20–18 against Newcastle at Bankwest Stadium.[32]
Cook played 23 games for South Sydney in the 2020 NRL season. Cook played in the club's third straight preliminary final but the club once again fell short of a grand final appearance losing to Penrith 20–16.[33]
Cook was again selected to play for New South Wales in the 2020 State of Origin series. In game 1 of the series he scored the opening try, but NSW lost the match 18–14. He played all three games in the series as New South Wales suffered a shock 2–1 series defeat.[34]
In round 6 of the 2022 NRL season, Cook scored his first career hat-trick in South Sydney's 36–16 victory over Canterbury.[37]
On 29 May, Cook was selected by New South Wales to play in game one of the 2022 State of Origin series. Cook played in all three games as New South Wales lost the series 2-1[38]
Cook played 23 games for South Sydney in the 2022 NRL season including all three of the clubs finals matches as they reached the preliminary final for a fifth straight season. Souths would lose in the preliminary final to eventual premiers Penrith 32–12.[39]
2023
After not being selected by New South Wales for game one of the 2023 State of Origin series, Cook was chosen to play in game two after Apisai Koroisau was ruled out of the series with a suspected broken jaw.[40]
Cook played a total of 23 games throughout the year as South Sydney finished 9th on the table and missed the finals.[41]
2024
After South Sydney started the season poorly winning only one match from their opening five games, Cook was left out of the starting 17 for the clubs round 6 game against Cronulla.[42]
On 19 June, Cook signed a two-year deal to join St. George Illawarra starting in 2025. Cook played a total of 23 games for South Sydney in his final year at the club as they finished 16th on the table. Cook's last game for South Sydney was a 36-28 loss against arch-rivals the Sydney Roosters.[43]