Larkin was drafted #18 overall by the Atlanta Hawks in the 2013 NBA Draft. He was traded to the Dallas Mavericks where he played from 2013 to 2014. Larkin played for the New York Knicks from 2014 to 2015 and the Brooklyn Nets from 2015 to 2016. He played for Baskonia from 2016 to 2017 where he was All-Spanish League Second Team. Larkin joined the Boston Celtics in 2017. He is the son of Barry Larkin who is a Baseball Hall of Famer.