The deal, announced early Tuesday, will pay Timmons $50 million through 2016. Timmons is the second linebacker to sign an extension with the Steelers in the last month. Teammate LaMarr Woodley agreed to a six-year, $61.5 million contract on Aug. 5.
The 26-year-old Woodley and the 25-year-old Timmons are considered the young core of a linebacker group that includes 33-year-old James Harrison, 31-year-old Larry Foote and 36-year-old James Farrior.
The contract extensions to Timmons and Woodley were made likely because of contract restructuring by several of their teammates, including Harrison and quarterback Ben Roethlisberger
Timmons, selected with the 15th overall pick of the 2007 NFL Draft, had 95 tackles and three sacks last season.