Longabardi joins the Cavaliers after head coach David Blatt was surprisingly fired last week and Lue elevated to replace him. He is expected to take over Lue's role as the defensive specialist.
Longabardi spent two-plus seasons as an assistant coach with the Phoenix Suns before he was let go last month in a coaching staff shake-up.
For six seasons, Longabardi was as an assistant with the Boston Celtics under Doc Rivers, including four years when Lue was also on the staff. Before Longabardi arrived in Boston, he worked under Jeff Van Gundy as an assistant with the Houston Rockets.