Coming off a successful season with the Oakville Rangers Midget AAA, Luff split his time between the Rangers and the Oakville Blades of the Ontario Junior Hockey League for the 2013–14 season. On June 9, 2014, Luff signed a contract with the Blades for the 2014–15 season, however he chose to commit to the Belleville Bulls of the Ontario Hockey League who had drafted him in the OHL Draft. In his rookie year with the Bulls, Luff was named a finalist for the Rookie of the Year, with the award eventually going toAlex DeBrincat. Following the 2014–15 season, the Bulls were re-named the Hamilton Bulldogs. After going undrafted in the NHL Entry Draft, Luff attended the Los Angeles Kings development and training camp as a free agent. He eventually signed a three year entry level contract with the Kings on September 23, 2016, becoming the first Bulldog to sign an NHL contract. Luff returned to the OHL for the 2016–17 season where he played only 45 games due to a shoulder injury and concussion. Despite his shortened season, Luff was re-assigned to the Kings American Hockey League affiliate, the Ontario Reign on April 7, 2017. Luff began the 2018–19 season with the Ontario Reign after being assigned there from the Kings training camp. Luff was recalled to the NHL on November 3, 2018, and he made his NHL debut that night against the Columbus Blue Jackets. Luff played 9:43 in his debut to help the Kings win 4–1 over the Blue Jackets. After playing in three games, Luff was reassigned to the Ontario Reign on November 11 only to be recalled three days later on November 14. Luff recorded his first career NHL goal in a 2–0 win over the St. Louis Blues on November 19. On November 25, in a 5–2 win over the Edmonton Oilers, Luff recorded his fourth goal in the same number of games, becoming the fifth Kings rookie to do so since Jimmy Carson in 1987. His streak ended the following game against the Vancouver Canucks. After appearing in 30 games for the Kings, and recording 10 points, Luff was reassigned to the Ontario Reign on February 8, 2019.
