The deal includes $40.5 million guaranteed, according to the source.
The All-Pro linebacker has started every game for the 49ers since he was drafted in 2018. Warner, 24, had 125 tackles last season and earned his first Pro Bowl nod. He tallied 124 tackles in his rookie season and 118 tackles in 2019 to help the 49ers reach the Super Bowl.
Warner, a third-round draft pick out of BYU, was entering the last year of his contract.
This is a developing story.