The 33-year-old has huge Premier League experience, having made 340 appearances in the competition, kept 127 clean sheets and won the title twice with Manchester City.
He jointly holds the record for the most Golden Glove awards, with four, the same as Petr Cech.
“Firstly, I just want to say thank you to the club for seeing something in me,” Hart told the club’s official website.
“No getting away from it, it’s been a difficult couple of years for me personally on the football field, but I feel I’ve got so much to give.
“You can’t help but get excited at this club. Off the field, doing everything right, tremendous training ground, one of the world’s greatest stadiums, some of the best players you can get in football.
“I think we can work together as a team and work together as a unit and the sky’s the limit, it has to be.”