Heenan suffered further injury setback during the off-season and had further surgery on his shoulder. He finally made his return on New Year's Day 2016 in a 2015–16 Pro12 game against Leinster. Heenan did not feature in the 2015–16 Challenge Cup as he was not registered for the competition due to his injury troubles. Heenan went on to make 11 appearances in the Pro12 however, including playing the full 80 minutes in the Grand Final as Connacht won the competition for the first time.