Jackson traveled to Seattle on Tuesday to visit the Seahawks and take a physical with the two-time reigning NFC champions, a source confirmed to ESPN's Jim Trotter.
NFL.com first reported Jackson's plans earlier Tuesday.
Jackson, an eight-year veteran, became a free agent on Monday, when the Bills cut the respected team leader and fan favorite.
Jackson and Lynch have been close friends since 2007, when both broke into the NFL with the Bills. Lynch was Buffalo's first-round pick, and Jackson made the Bills' roster after spending the previous year on the team's practice squad.
The two shared starting duties during the 2009 season, and Jackson took over as the starter after the Bills traded Lynch to Seattle.
The two have stayed in touch, with Jackson noting that he and Lynch exchange texts regularly. At age 34, Jackson was the league's oldest running back last season.
The Bills restocked their backfield by acquiring LeSean McCoy in a trade with the Philadelphia Eagles in March. Jackson was also set to make a $2.5 million base salary in the final season of his contract, which was deemed expensive for a backup.
Although slowed by injuries the past few years, Jackson is a versatile rusher and receiver as well as a dependable blocker. Jackson's 5,646 rushing yards rank third in Bills history; he is fourth with 30 rushing touchdowns.
Information from The Associated Press was used in this report.