On March 31, 2015, upon completing his senior year LaLeggia signed his first professional contract in agreeing to a two-year entry-level deal with the Edmonton Oilers.

[1] During his first season with the Oilers organization, LaLeggia recorded 27 points in 63 games with the Bakersfield Condors of the American Hockey League.

[3] On July 1, 2018, having left the Oilers in the off-season as a free agent, LaLeggia agreed to a two-year, two-way contract with the St. Louis Blues.

[4] Following the conclusion of his contract with the Blues, having played exclusively with affiliate, the San Antonio Rampage, LaLeggia opted to pursue a European career, by signing a one-year contract for the remainder of the 2020-21 season with Swedish club, Rögle BK of the SHL, on January 17, 2021.

[6] During his second season with Timrå IK in the 2022–23 campaign, LaLeggia registered 2 goals and 5 points through 9 games before transferring to newly promoted HV71 on October 19, 2022.