Simon played three seasons in the QMJHL with the Cataractes before he was signed as an undrafted free agent to a one-year contract with the San Diego Gulls of the American Hockey League on September 25, 2018. In his first professional year with the Gulls in the 2018–19 season, Benoit impressed by leading the Gulls in Plus/Minus with +16 and collecting 2 goals and 16 points through 65 regular season games. On March 8, 2019, he was signed by the Ducks to a three-year, entry-level contract beginning in the 2019–20 season.

During the 2020–21 season, while in his third year with the San Diego Gulls and adding dependable defensive play on the blueline, Benoit was recalled by the Ducks to make his NHL debut on April 29, 2021. While appearing on the Ducks third defensive pairing, Benoit went scoreless with 12 minutes time on ice in a 3–2 victory over the Los Angeles Kings. In the following 2021–22 season, on October 28, 2021, Benoit scored his first NHL goal in his eighth game with the Ducks, a game tying goal, against the Buffalo Sabres in a 4–3 OT loss. Benoit played his first full season with the Ducks during the 2021–22 season.

Having played five seasons within the Anaheim Ducks organization, as a pending restricted free agent Benoit was not tendered a qualifying offer by the team and was released as a unrestricted free agent. He was signed on August 28, 2023 to a one-year, $775,000 contract by the Toronto Maple Leafs. Benoit failed to the make the team out of training camp and was placed on waivers. After going unclaimed, Benoit was assigned to the Maple Leafs' AHL affiliate, the Toronto Marlies. After Timothy Liljegren was injured, Benoit was recalled by the Maple Leafs on November 4. He made his debut with the Maple Leafs in a 6–5 win over the Tampa Bay Lightning on November 6. After 54 games and leading the Leafs in hits with 205 at that juncture in the season, Benoit was rewarded with a three-year extension with the club worth an average value of $1.35 million per year.