He previously played for the Wests Tigers, North Queensland Cowboys and the Gold Coast Titans in the National Rugby League.

In Round 13, Marsters made his NRL debut for the Wests Tigers against the St George Illawarra Dragons, playing off the interchange bench in the 16–12 loss at ANZ Stadium.

Marsters was said to be one of the most improved players in the game in 2018, and, "has been stellar in 2018, to the point he made his New Zealand Test debut and has claims on being one of the form centres right across the NRL.

[17] Following their round 10 loss to the Penrith Panthers, Marsters was dropped by interim head coach Josh Hannay.

[18] It was said, "Brought to Townsville to sharpen the Cowboys lacking backline and provide more attacking threats on the edges, Marsters struggled to live up to the hype.

Defensive lapses plagued his start at the club, with his combination on the right side with Kyle Feldt the worst in the competition for conceding tries.

[20] Interim coach Josh Hannay explaining his absence by saying, "He is an extremely gifted player, Esan, but he can clock off at times out on the field.

[25] Marsters' cousin, Steven, is a professional rugby league player for the South Sydney Rabbitohs.