Macklin made his first appearance for Ulster against Aironi on 19 September 2011. Macklin scored his first try for Ulster on 17 December 2011, finishing off a 46–20 win against Aironi in the Heineken Cup. He was rewarded for a series of fine substitute appearances with his first start on 26 December 2011 against Leinster. Macklin came on as a substitute in the 22–19 win against Edinburgh to reach the
Heineken Cup final. Ulster lost the final in a 42–14 defeat to three-time champions Leinster Rugby. Macklin did not feature in that match because coach Brian McLaughlin favoured Declan Fitzpatrick. ==Houston==