[3] Rein made his NRL first grade debut for the St. George Illawarra Dragons on 12 March 2011 at Skilled Park, Robina in Round 1 of the 2011 Telstra Premiership,[1] when he came on for the final thirty minutes of their 25–16 win, making 18 tackles.

[6] Rein was a member of The Penrith Panthers side that won the 2017 Intrust Super Premiership NSW and The 2017 NRL State Championship.

Rein made a total of 18 appearances for the Gold Coast in the 2019 NRL season as the club endured a horror year on and off the field.

During the halfway mark of the season, head coach Garth Brennan was sacked by the club after a string of poor results.

[11][12] Rein played nine games for the Gold Coast in the 2020 NRL season as the club finished ninth on the table and missed the finals.