On August 5, 2015, Jefferson signed with the Cleveland Cavaliers. The Cavaliers finished the regular season with a 57–25 record and made it through to the 2016 NBA Finals with a 12–2 playoff record. Jefferson started Game 3 of the NBA Finals in place of the injured Kevin Love. Jefferson gave the Cavaliers a boost in 33 minutes, scoring nine points with eight rebounds, as the Cavaliers cut the Golden State Warriors' advantage in the series to 2–1 with a 120–90 win. Despite going down 3–1 in the series following a Game 4 loss, the Cavaliers won the series in seven games to become the first team in NBA history to win the championship after being down 3–1.