The group, which owns the national newspaper titles the Daily and Sunday Mirror and The People, said proceeds would go towards paying off Trinity's £768m debts.
The titles include the Derby Trader and the Northampton Herald and Post. A group spokesperson said, "These titles are peripheral to the core business."
The deal is subject to the approval of Patricia Hewitt, the secretary of state for trade and industry.
Trinity Mirror also owns regional newspaper titles including the Daily Record, Western Mail, Wales on Sunday, the Birmingham Evening Mail, Sunday Mercury, the Liverpool Echo, and The Journal and Sunday Sun in Newcastle.