The 28-year-old was a standout performer for the Latics last term, scoring 10 goals in 32 league appearances.
Keane had a previous loan spell with the club in 2013, and then joined Wigan last October after training with the first team during pre-season.
The forward told the club website after signing his new deal: "I'm absolutely delighted. On the back of last season, I was hoping to get it sorted so I'm glad it's come around quite soon, and I cannot wait to get back into pre-season and crack on from there.
"I think being at the Club last season, with the manager and all of the players, I think we really found our form in the last couple of months and now we are wanting to build on that.
"Obviously to stay up last season was really good, and we are just looking forward to next season to get the fans back. It's going to be a massive boost with the new ownership and it should hopefully be a good atmosphere around the place.
"I know the Club are ambitious and I am hoping to be a part of that. I feel like I was producing good performances last season, and I know I've got the capability to improve on that next season and keep moving forward."
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