The six-foot-one, 232-pound linebacker/defensive end said Friday he signed a three-year deal with the Hamilton Tiger-Cats shortly after becoming a free agent.
Williams, 27, spent the last three seasons with the Saskatchewan Roughriders and was the team's second-leading tackler in 2012 with 59.
"I would've like to stay in Saskatchewan but going to Hamilton is a good fit for me," Williams said. "It's a lot closer to home and I'm going to a very good team.''
Saskatchewan selected Williams first overall in the 2010 CFL draft out of Queen's.
The Toronto native capped his university career by helping Queen's capture the Vanier Cup in 2009.
Williams began his college career at the University of Houston.
The Ticats also signed free-agent defensive tackle Brian Bulcke, who spent last season with Calgary. The native of Windsor, Ont., who played his college football at Stanford, had three sacks and 29 tackles in 22 career regular-season games with the Stampeders.