He made 39 Championship appearances for the Potters during the past two seasons and previously played for Charlton and QPR.
“I came down here a couple of weeks ago and I was blown away by the facilities and what the manager had to say, and I’m looking forward to getting going,” Cousins told the League One club’s website.
“It’s a new challenge for me but a challenge I’m looking forward to.
“I’ve been to the training ground and I’ve been around the DW Stadium and the vibe that I’m getting is really good. I can’t wait to get started.”