Cowart was born January 8, 1944, in Rockport, Mississippi; she and her family later relocated to Inkster, Michigan.[3] As the eldest daughter in her family, she was influenced by singers such as Mahalia Jackson, Billie Holiday, and Sarah Vaughan.[3] While attending Inkster High School, she helped form the girl group The Casinyets, which later became The Marvels, and then, The Marvelettes.[4]
Cowart can be heard on The Marvelettes "Please Mr. Postman", which became a Number One Hit on the Billboard Charts and notably Motown's first number one hit.[5] Due to stress of touring and after an embarrassing statement she made on Dick Clark's American Bandstand, Cowart left the group in 1963.[3][6][7]
After leaving the Marvelettes, Cowart earned her high school diploma after dropping out of high school to tour, married Larry Motley, and became active in church activities and in her Inkster community.[3] As of 2026, Cowart-Motley is the sole living original member of The Marvelettes.[8]