The 22-year-old has been much in demand this summer and turned down a £6million move to Sunderland last month.
Baines played no part in Wigan's friendly victory over Leeds on Saturday. He was reportedly suffering from a hamstring strain but his absence at Elland Road fuelled speculation that a move was imminent.
Wigan manager Chris Hutchings was keen to keep the highly-rated player at the JJB Stadium and recently paid tribute to his professionalism amid all the transfer talk.
"Leighton is a first-class pro and a first-class person and, despite all the speculation and rumour surrounding his future, he has remained professional throughout and as ever is a joy to work with," Hutchings said.
"I have coached him since he first broke into the first team as a young apprentice and taken great satisfaction in how he has developed as a player and an individual."