[3] Grimaldi played AAA Hockey for Detroit Little Caesars during the 2008–2009 season, collecting 43 points with 17 goals and 26 assists in 31 games.

[11] In the 2014–15 season, Grimaldi made his professional debut with the Panthers AHL affiliate, the San Antonio Rampage.

[14] After attending his first training camp with the Avalanche, Grimaldi was reassigned to affiliate and former AHL club, the San Antonio Rampage, on September 30, 2016, to begin the 2016–17 season.

As a group IV free agent, Grimaldi opted to leave the Avalanche and agreed to a one-year, two-way contract with the Nashville Predators on July 1, 2018.

In preparation for the 2022–23 season, Grimaldi agreed to join the Anaheim Ducks on a professional tryout basis, attending training camp and the pre-season.

After impressing through the Ducks pre-season, Grimaldi was signed to a one-year AHL contract with affiliate, the San Diego Gulls, on October 15, 2022.

[22][23] Grimaldi was leading the languishing Gulls in scoring, notching 27 goal and 56 points through only 54 games before he was traded to the Rockford IceHogs on March 2, 2023.

On October 11, 2024, he agreed to a professional try-out to join the Cleveland Monsters of the AHL, primary affiliate to the Columbus Blue Jackets.

[5] In the gold medal game versus Sweden, Grimaldi had one goal and one assist as the United States triumphed by a 3–1 mark.

[27] A decade after his last appearance in international junior competition, Grimaldi accepted an invitation to join the senior national team at the 2023 IIHF World Championship.