The 24-year-old, who spent last season on loan at the Reebok Stadium and was named Player of the Year, has signed a four-year deal to become the club's sixth summer signing
The 24-year-old midfielder spent last season on loan at the Reebok Stadium, making 39 appearances and winning the club's player of the year award, and the club have now sealed a permanent deal with the player signing a four-year contract.
Bolton manager, Dougie Freedman, was full of praise for Spearing and expressed his gratitude to the board for making the transfer possible.
"Jay wanted to come here and wanted to play for the Bolton jersey. He brings qualities to the football club both on and off the field," Freedman told the club's official website.
"He turned down a few other clubs to come here and he knows and likes the style of our management team.
"We really have to thank the board and owners on this one. The support we’ve had has been great in helping us to acquire such a fantastic young player."
Spearing, who will wear the No.6 shirt, is Bolton's ninth signing of the summer.