Ryan was granted a place in Leinster's academy for the 2016–17 season, but injury meant his season was badly disrupted. Nonetheless, he was given a full senior contract ahead of the 2017–18 season, despite having completed only one of the normal three academy years.[5]
Ryan lined out for Munster against the Ireland U20 team in Thomond Park on his way back from a hamstring injury to gain valuable game time ahead of Ireland's summer tour to Japan. Ryan has played for Munster and Ireland before making his competitive debut for Leinster in September 2017.[6]
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.[7] 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.[8] In making his debut, Ryan became the first Irish player since Michael Bent in 2012 to make his senior Ireland debut before making his provincial debut.[9]
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.[10] He captained Ireland for the first time in their loss to England in the Autumn Nations Cup.
In November 2023 Ryan was named Leinster club co-captain alongside Garry Ringrose following the retirement of Johnny Sexton.[11]
