Peace became chairman in 2002 and had been looking for around £200million for West Brom after coming close to selling the club last summer.
He said: “It has been a tremendous privilege to lead the Albion. I am proud that 11 of my 15 seasons as Chairman have been spent in the Premier League whilst three others brought automatic promotion from the Championship.
“Guochuan Lai has been a supportive partner during the handover process and we have both done everything possible to move the club forward.
“Guochuan, John Williams, my board colleagues, our staff and supporters have my very best wishes for the future.”