Last week Watts extended his contract with the Vikings which was supposed to keep him at the club until 2013, but has suddenly decided to return home to Australia.
Watts said: “I would like to thank Widnes Vikings for the opportunity, but I need to return home for personal reasons.
“As I suggested recently, I genuinely believe the club will be a huge force within the next few years and go on to achieve great things in the game.
“Unfortunately, I won’t be a part of that but I hope the fans continue to show the passion and commitment that I have witnessed in my short time there and help steer this great club back in the right direction.
“I wish all concerned at Widnes Vikings well for the future.”
The former North Queensland Cowboy suffered an injury 10 minutes into his Super League debut against Salford earlier this year.