 Farrell made his competitive debut for Munster on 1 September 2017, starting the provinces opening 2017–18 Pro14 fixture against Benetton in Irish Independent Park, Cork.Farrell scored his first try for Munster in their fixture against South African side Cheetahs on 9 September 2017, helping the province to a 51–18 win in Thomond Park.He was ruled out for 6–8 weeks following a knee injury sustained whilst playing for Ireland.