Leonard was originally first eligible to be drafted in
2016, but was not selected while playing for the
Green Bay Gamblers of the
United States Hockey League. After two years with the Gamblers, Leonard joined the
University of Massachusetts Amherst ("UMass"), playing for their ice hockey team, the
UMass Minutemen while studying Communications and Sport Management. While with the Minutemen, Leonard caught the attention of the
San Jose Sharks, who drafted him in the sixth round, 182nd overall in the
2018 NHL entry draft despite not having any contact with Leonard during the predraft process. In his third year at UMass, Leonard was a finalist for the
Hobey Baker Award and lead all NCAA players in goals, with 27. On March 31, 2020, Leonard decided to forgo his final year of college eligibility and was signed to a three-year entry-level contract with the Sharks. Leonard made the opening night roster and made his NHL debut against the
Arizona Coyotes on January 14, 2021, playing on a line with
Evander Kane and
Tomáš Hertl. Leonard posted two points in his debut, assisting on goals by both his linemates, helping the Sharks to a 4–3 shootout victory. After his second full professional season within the Sharks organization, on July 8, 2022, Leonard was traded along with a
2023 third-round pick at the
2022 NHL entry draft to the Nashville Predators in exchange for
Luke Kunin. On July 18, 2022, Leonard was signed as a
restricted free agent to a one-year, two-way contract with the Predators for the season. He spent the majority of the season with Nashville's
American Hockey League (AHL) affiliate, the
Milwaukee Admirals, scoring 17 goals and 27 points in 67 games. He got into six games with Nashville At the end of the season, again a restricted free agent, he was not given a qualifying offer by Nashville and became an
unrestricted free agent. Leonard signed a one-year, two-way contract with the Arizona Coyotes on July 3, 2023. He was recalled by Arizona on March 12, 2024, after an injury to
Barrett Hayton. Leonard made his Coyotes debut on March 14 versus the
Detroit Red Wings. He scored his first goal with the Coyotes against
Jake Oettinger in his fourth game, a 5–2 loss to the
Dallas Stars on March 20. As a free agent at the conclusion of his contract with the Coyotes, Leonard was unable to garner an NHL deal and was signed to a one-year AHL contract with the
Charlotte Checkers, the primary affiliate to the
Florida Panthers, on July 2, 2024. In the
2024–25 season with the Checkers he was named to the league's Second All-Star Team after registering 61 points through 72 regular season games. Following a breakout season offensively, Leonard secured an NHL contract as a free agent, agreeing to a one-year, $775,000 contract with the Detroit Red Wings on July 1, 2025. ==Personal life==