Butler was selected in the
Ireland under-20s squad for the
2022 Six Nations Under 20s Championship when it was announced in January 2022, and made his competitive debut for the under-20s in their tournament-opening 53–5 win against
Wales on 4 February, coming on for starting fly-half Charlie Tector in the 52nd minute and converting Ben Brownlee's 79th minute try. Butler was as a replacement in Ireland's 39–12 win against
Italy on 25 February, scoring two conversions, the 42–27 away win against
England on 12 March, and the 59–5 home win against
Scotland on 20 March that secured a
Grand Slam for Ireland. Butler was retained in the squad for the Under-20s Summer Series when it was announced in June 2022, and started in Ireland's opening 42–21 defeat against
France on 24 June, scoring one conversion during the match. ==Honours==