Ireland has failed to make the expected impact at Villa Park and will join up with former boss Mark Hughes at Stoke.
Ireland played under Hughes at Manchester City.
“Stephen is a player that Mark knows really well and, when the opportunity arose, he was keen to add him to his midfield and attacking options,” chief executive Tony Scholes told Stoke’s official website.
“Arguably the most successful period of Stephen’s career to date was when he played for Mark at Manchester City and we hope that he can rediscover that form.”
