Janikowski, the Raiders' all-time leading scorer, was on injured reserve last season because of a back injury. He will become an unrestricted free agent.
Giorgio Tavecchio, 27, replaced Janikowski this past season and made 16 of 21 field-goal attempts, with a long of 53, and missed only one of his 34 extra-point tries.
Janikowski, who turns 40 on March 2, was selected by the Raiders with the 17th overall pick in the first round of the 2000 NFL Draft out of Florida State. Raiders owner Al Davis made the decision to select him, overruling then-coach Jon Gruden, who reportedly wanted either wide receiver Sylvester Morris or running back Shaun Alexander.
Gruden recently returned as Raiders head coach.
The left-footed Janikowski has 1,799 points, including 414 field goals, both ranking 10th in NFL history. He played in a franchise-record 268 games in 18 seasons.
Janikowski took a $1 million pay cut at the end of training camp in August and made $3 million in 2017. He was placed on injured reserve the day before the season opener.