In the 2007–08 season, Grimaldi turned pro officially and signed with the Rochester Americans, an affiliate of the Buffalo Sabres, and was later sent down to the Elmira Jackals (Ottawa Senators) of the ECHL.

Grimaldi played in 36 games recording 15 points as a rookie with the Jackals and made his AHL debut with the Rochester Americans and Albany River Rats, an affiliate of the Carolina Hurricanes.

On January 15, 2008, Grimaldi was traded to fellow ECHL team the Fresno Falcons, affiliate to the San Jose Sharks.

[2] Grimaldi started the 2008–09 season with the Cincinnati Cyclones of the ECHL before returning to the Jackals placing third on the team with 101 penalty minutes.

Following that year, Grimaldi joined the Nottingham Panthers of the Elite Ice Hockey League (EIHL) for the 2013–2014 season.

He played seven games before feuding with Coach Corey Neilson which led to his release, tallying 8 points (2 goals, 6 assists).

On January 3, 2015, playing against his former team the Nottingham Panthers, Grimaldi made an open-ice hit to the head of Evan Mosey which led to being challenged to fight by Max Parent.