The 29-year-old back-row forward opted to link up with his old Wigan team-mate Denis Betts, the Vikings head coach, at the Halton Stadium after experiencing a major fall-out with the Warriors.
Hock was heavily criticised by Wigan, who stood by him during his two-year drugs ban and revealed he had refused to train with them in the close season in order to facilitate a move. After being unveiled at a press conference, Hock declined to comment on the breakdown of his relationship with his home-town club but spoke of his excitement at a season-long move to Widnes.
"Things have happened at Wigan. It's a fresh start and I'm really looking forward to it," said Hock. "There were a few clubs on the phone but I had my heart set on Widnes. I like being in a good environment and I've got a lot of friends here. I can't wait to get playing.
"I know Denis really well. I've played with him. That was one of the reasons. It was an easy choice for me."
Hock will also link up with former Wigan stand-off Kevin Brown, his brother-in-law with whom he is currently sharing a house in Orrell. He is currently sidelined with a shoulder injury but has set himself a target of making his Widnes debut against St Helens at the Halton Stadium on February 10.
"I'm looking at the second game," he said. "I've had my medical and it's not as bad as they thought. I had four pieces of bone taken out and some cartilage cleaned up. I'm running and doing my rehab and I'll start doing contact soon."
Hock, who made a successful return to the Wigan team in 2011 and regained his England place last season, was lined up for a move to Australian club Parramatta in the winter but it fell through.
Wigan chairman Ian Lenagan said: "Gareth Hock has made it clear in face-to-face discussions with me and via his agent that he has no intention of playing for the Wigan club. This is hugely disappointing to me, to the Wigan fans and to the club who have all treated him well.
"We have gone to unique lengths to help him get his life back on track after his ban two years ago, including increasing his contract voluntarily on two separate occasions to help him financially against a backdrop of his threats to leave. The Wigan club has consistently supported the player and has done all that any club could be asked to do."