Born in Bridgend, Jenkins began playing rugby for Porthcawl RFC juniors, where he progressed through the age groups.

[2] While playing for Hartpury, Jenkins was contacted by Exeter head coach Rob Baxter, and he linked up with their team in 2021.

[6][7] On 12 November 2022, Jenkins set the Premiership record as youngest player named captain, at 19 years and 342 days old, in a victory over London Irish.

[8] Jenkins was called up to the Wales under-20 squad for the first time ahead of the 2021 Six Nations Under 20s Championship, making his debut in the 25–8 victory over Italy.

[15] On 16th January, 2024, in the absence of Jac Morgan through injury, Jenkins was named captain of the Wales squad for the 2024 Six Nations Championship.