The 40-year-old reportedly met with the Seahawks on Tuesday.
Janikowski, nicknamed "The Polish Cannon," is one of only three players remaining in the NFL from the 2000 draft, in which he was drafted 17th overall out of Florida State by the Raiders.
The Raiders' all-time leading scorer with 1,799 points, 11th in NFL history, he played in a franchise-record 268 games, but did not play last season after going on injured reserve in the preseason because of a back injury.
Janikowski took a $1 million pay cut late in training camp and made $3 million last season. He had signed a four-year, $16 million extension in 2014.
His 63-yard field goal at Denver in 2011 tied the NFL record for longest field goal at the time, and Janikowski has made 80.4 percent of his field goal attempts (414 of 515) and 98.9 percent of his extra-point attempts.
Janikowski, whose 55 field goals of at least 50 yards are an NFL record, missed only four games in his career until last season, two as a rookie, one in 2001 and another in 2011.