In 1991, Williams-Isom joined Robinson, Silverman, Pearce, Aronsohn, and Berman. She joined Kalkines, Arky, Zall & Bernstein in 1994. In 1996, Williams-Isom joined the New York City Administration for Children's Services as the director of the Office of Community Planning and Development. She later served as special counsel to the commissioner. In 2006, under during the Mayoralty of Michael Bloomberg, she was promoted to deputy commissioner of community and government affairs at the New York City Administration for Children's Services.
