The 28-year-old made just three appearances for the Black Cats last season, a total which cost him his place as Republic of Ireland's number one shot-stopper.
However, with current Sunderland number one Simon Mignolet nearing a move to Liverpool, a place could open up in the team for Westwood.
"I love it at Sunderland, but if I'm not going to play... It's a tough decision, but I need to play football, I think that's evident in itself," he told Press Association Sport.
Westwood joined Sunderland from Coventry City in 2011.