Shearer was born in Toronto and grew up in New York State. She studied at Skidmore College and at Bennington College, a center of modern dance.
A onetime member of the pioneering Humphrey-Weidman company and an assistant to Agnes de Mille, she made a well-received solo recital debut at Carnegie Hall in 1941. Two years later, she moved to the Chicago suburb of Winnetka, and she danced and taught in the Chicago area for the rest of her career. She formed her own company there in 1959.
In recent years, she wrote for Ballet Review and worked on Without Wings the Way Is Steep, a three-volume autobiography.
"A performance for me was a complete emptying out, [after which] I had to have time to recuperate...in order to have the full amount to give the next time," she wrote, according to the Skidmore alumni magazine. "This balance of emptying out and filling up again has stood me in good stead, so that I not only still feel like giving, but actually can give, to the world in general and certain individuals in particular."