Cleveland Cavaliers (2015–present)
On January 5, 2015, Smith was traded to the Cleveland Cavaliers in a three-team trade that also involved the Knicks and the Oklahoma City Thunder. Cleveland received Smith and Iman Shumpert from the Knicks and a first-round pick in the 2015 NBA draft from the Thunder, while Cleveland sent Dion Waiters to Oklahoma City and Lou Amundson, Alex Kirk, and a 2019 second-round draft pick to the Knicks, and the Thunder sent Lance Thomas to the Knicks. Two days later, he made his debut for the Cavaliers in a loss to the Houston Rockets.
On April 27, 2015, Smith was suspended for the first two games of the Eastern Conference semi-finals after he swung his arm and made contact with the head of Celtics forward Jae Crowder in Game 4 of their first-round series against Boston. In Game 1 of the Eastern Conference Finals against the Atlanta Hawks on May 20, Smith set a Cavaliers franchise playoff record with eight three-pointers as he finished the game with 28 points off the bench to help lead the Cavs to a 97–89 win. Smith helped the Cavaliers sweep the Hawks and reach the NBA Finals for just the second time in franchise history. The Cavaliers faced the Golden State Warriors in the 2015 NBA Finals, but they lost the series in six games.
On September 2, 2015, Smith re-signed with the Cavaliers. On November 23, 2015, he scored a then season-high 26 points in a 117–103 win over the Orlando Magic. On January 2, 2016, in another win over the Magic, Smith hit one three-pointer which moved him past Nick Van Exel (1,528) for 22nd place on the all-time three-pointers-made list. Two days later, he scored 24 points on eight three-pointers in a 122–100 win over the Toronto Raptors. On January 8, he scored a season-high 27 points in a 125–99 win over the Minnesota Timberwolves. He matched his season high of 27 points on April 3 in a 112–103 win over the Charlotte Hornets. In Game 2 of the Cavaliers’ first-round playoff series match-up with the Detroit Pistons, Smith scored 21 points and made seven of Cleveland’s NBA playoff record-tying 20 three-pointers in a 107–90 win.[
45] After sweeping Detroit, they moved on to the second round, where in Game 2 of their series against the Atlanta Hawks, Smith hit seven of the Cavaliers’ NBA record 25 three-pointers (the most in any regular season or playoff game) to help Cleveland take a 2–0 series lead over the Hawks. The Cavaliers went on to sweep the Hawks, and then defeated the Toronto Raptors 4–2 in the Eastern Conference Finals to advance to the 2016 NBA Finals. In Game 3 of the NBA Finals, with the Cavaliers down 2–0 to the Golden State Warriors, Smith scored 20 points in a 120–90 win to help the Cavaliers cut the deficit to 2–1. The Cavaliers went on to win the 2016 NBA championship, despite going down 3–1 in the series following a Game 4 loss, as Smith won his first NBA title.