Sky Sports sources revealed earlier on Friday that the Scottish full-back was having a medical with Wigan, and he has joined the Latics on a one-year deal.
Crainey left Blackpool after a six-year spell and is relishing the challenge of battling for promotion back to the Premier League and competing in the Europa League with the FA Cup winners.
"It's a big challenge for me personally, but after six good years at Blackpool I felt it was time for a new challenge at this stage of my career and I'm delighted for that to be at Wigan Athletic," he said.
"The Championship is a gruelling division, with tough games every week, but that and the chance to play European football, is a challenge I'm really looking forward to.
"I've played against Wigan Athletic on a few occasions so I know how much the fans back their team and I'm sure they'll do the same this season which is what we need to produce the performances on the pitch."
Crainey has become Owen Coyle's second signing as Wigan boss after midfielder Chris McCann agreed to link up with the Latics earlier in the week.