Sometimes credited as Tonya Lee Williams, she is best known for her role as Dr. Olivia Barber Winters on the American daytime drama The Young and the Restless from 1990 to 2005 and 2007 to 2012.

As a teenager she modeled in Eaton's catalogues and danced on a television series called Boogie!

Williams' television debut was as a host of the Canadian children's show Polka Dot Door, from 1980 to 1983, after graduating from Ryerson Polytechnical Institute in 1979.

Williams won the NAACP Image Award for Outstanding Actress in a Daytime Drama Series in 2000 and 2002.

[2] In January 2025, Williams was named as the recipient of the Toronto Film Critics Association's Company 3 TFCA Luminary Award, in honour of her work with Reelworld and her other efforts to advocate on behalf of people of colour in the Canadian film industry.