The deal, which runs through the 2014 season, was announced Tuesday.
Spillman, 25, has played all 27 regular season games for the 49ers since he
was claimed off waivers from the San Diego Chargers on Oct. 12, 2010.
'C.J. is a high-energy, productive player with a strong team-first mentality
who is still developing,' 49ers General Manager Trent Baalke said in a
statement. 'We are pleased to come to terms with C.J. for another three years,
and look forward to his continued contributions to our organization, both on
and off the field.'
Spillman made 18 tackles in 16 games for San Francisco last season. He has 50
career tackles in 37 games for the 49ers and Chargers, including one start in
his rookie season in 2009.