The Northern Ireland youth international began his career as a youth with Motherwell before heading to Celtic, with whom he signed his first professional contract in July 2021. McLean featured in Celtic's under-18 team and was frequently included in European matchday squads, including the Champions League. He also played in the UEFA Youth League. At international level, he made his debut for the under-16s in a match with England. He then went on to play four times at under-17, including against Scotland, Italy and Albania in European qualifiers. He has also played for the under-18 squad. Kai had a short spell at Dunfermline after leaving Celtic in the summer.