Ryan made his competitive debut for Leinster on 2 September 2017, coming off the bench in the provinces opening 2017–18 Pro14 win against Dragons and playing for 21 minutes.

[6] In November 2023 Ryan was named Leinster club co-captain alongside Garry Ringrose following the retirement of Johnny Sexton.

[7] During his time as co-captain, Ryan experienced some difficulties such as referees refusing to interact with him due to excessive communication.

[11] Joe Schmidt called Ryan up to the senior Ireland squad for the first time ahead of the 2017 Summer Tour to the United States and Japan.

[12] On 10 June, in the one-off test against the United States, Ryan made his debut for Ireland, coming off the bench and scoring a try.