The Everwood star will appear as an ex-hockey player on the TNT drama, according to TV Guide.
His character Pete Rising now owns a professional hockey team, but his ruthless tactics bring him to the attention of Nate (Timothy Hutton) and his team.
Williams has previously appeared in episodes of Brothers & Sisters and Law & Order: Special Victims Unit, and also starred in short-lived Lifetime cop drama Against the Wall.
His episode of Leverage - titled 'The Blue Line Job' - is yet to be scheduled.
The show's first season will premiere on July 15, 2012. In the UK, Leverage airs on FX.
> Leverage gets fifth season renewal from TNT
Watch Leverage star Gina Bellman's recent interview with Digital Spy below: