Simpkins begun his career playing rugby union for Rotorua Boys High School first XV.

He was first spotted by North Queensland Cowboys scouts at the New Zealand 15s rugby league tournament in Rotorua in 2016.

[6] Simpkins made his debut from the bench in round 18 of the 2021 NRL season for Wests Tigers in their 42–24 victory over the Brisbane Broncos at Lang Park.

[7] Simpkins won the Queensland Cup starting at prop in the Norths Devils 34-20 grand final win over the Redcliffe Dolphins.

On 24 January 2022, it was revealed that Simpkins had allegedly been involved in a car accident in which he mounted the kerb and drove through a fence while also being unlicensed.