Stanley Cosgrove, held his first solo exhibition at the École des Beaux-Arts de Québec in 1939. Afterward, his works were exhibited with the members of the Contemporary Art Society. In the same year, he was granted a scholarship to study in Europe, but the outbreak of World War II forced him to change his plans and instead, he went to Mexico.

In Mexico, he had the privilege of learning fresco techniques from the famous Mexican master, José Clemente Orozco which had a significant impact on his art. As a result of Orozco's teachings, Stanley Cosgrove utilized thin layers of dry paint and subtle colors in his works.

After returning to Canada, he became a teacher at the École des Beaux-Arts de Montréal and focused mainly on still lifes, portraits, and landscapes. He skillfully executed these themes with softness and delicacy.