The Holland international had been linked to the club in January before an injury dealt a blow to the proposed move.
But Mark Hughes has now completed his first signing as new boss by capturing the 24-year-old for a fee of £3m.
Pieters told the club's official website: "I've always wanted to play in the Premier League.
"It's one of the hardest competitions to play in with some great players and teams and I'm really excited about it.
"I'm really looking forward to playing for this club. It's important for me that the first impression is good and I've got a great feeling about Stoke City.
"My first job is to defend but I always want to attack and contribute as much as I can for the team. I've played a couple of times in the centre of defence as well but left back is my position.
"I've had a few injuries but that's all in the past now; I feel really good and can't wait for my time as a Stoke City player to start."
PSV paid 2.5m euros for Pieters in 2008 and he has gone on to make 17 appearances for the national side.