Croker rose through the ranks for the Newcastle Knights, playing with their Harold Matthews Cup team in 2015, the S. G. Ball Cup side from 2016 to 2017, captaining the side in the latter year,[5] and finally the under-20s side from 2017 to 2019.[6] During those years, he also played for the New South Wales under-16s and under-20s teams.[6] In November 2017, he re-signed with the Knights on a 3-year contract until the end of 2020.[7] In 2020, he joined the Knights' NRL squad as one of their 6 allocated development players,[8] as he graduated to the Canterbury Cup NSW team.[9]
Croker played a total of 24 games for Newcastle in the 2023 NRL season as the club finished 5th on the table. Croker played in both finals games as Newcastle were eliminated in the second week of the finals by the New Zealand Warriors.[13]
2024
Croker played 17 games for Newcastle in the 2024 NRL season as the club finished 8th and qualified for the finals. They were eliminated in the first week of the finals by North Queensland.[14] On 2 October, Croker re-signed with the club on a one year deal.[15]