The second-seeded Tigers, who improved their record to 15-2-1, will be conference co-champs with top-seed Norwalk, which beat Wilton, 5-1, in the other semifinal.
Due to a shortened schedule caused by Hurricane Sandy there will be no championship game.
Kent Coleman gave the Tigers a 1-0 lead midway through the first half with a goal off an assist from Matt Wilson.
Seven minutes later, Adam Findlay pushed Ridgefield’s lead to 2-0 when he scored after receiving a pass from Joey DeVivo.
Ridgefield goalie Cal Dearth stopped all four Greenwich shots to earn the shutout.
The third-seeded Cardinals fell to 13-3-2 with the loss.