Spencer was born on June 24, 1965, in the Bronx, New York. In 1976, she was cast as Dee Thomas—the quick-witted younger sister—in the sitcom What’s Happening!!, which was inspired by the 1975 film Cooley High. Originally airing as a summer series, the show gained popularity and ran for three seasons. It later returned as What’s Happening Now!! from 1985 to 1988, where Spencer made recurring appearances as an older, college-aged Dee.

After the original series ended, Spencer and her mother spent some time living in Africa. She later pursued higher education at the University of California, Davis, with the goal of becoming a veterinarian—a career her late stepfather had encouraged. Following the end of What’s Happening Now!!, she went on to attend veterinary school at Tuskegee University in Alabama and officially became a veterinarian in 1996.