The 24-year-old Australian - signed last summer from Peterborough - has agreed a new two-year deal with the Latics.
Dickov told the club's official website: "I am delighted because James is an integral part of our plans for next season. We saw last season when James and Dean Furman were fit and played alongside each other that there was probably no better central-defensive pairing in League One.
"I would go as far as saying James can be as big as any other signing we make this summer."
Dickov added: "James received a number of other offers which did not surprise me. He could have been better off financially elsewhere but he wants to stay with us.
"The great thing about James is that he is fully committed whether in games or training and also to the club as he has shown by agreeing to sign for two years."