Seattle finalized a one-year, $750,000 deal with the 44-year-old Japanese star Wednesday that could increase to $2 million with incentives, a source told ESPN's Jerry Crasnick.
"The addition of Ichiro gives our team another versatile and athletic outfielder," Mariners general manager Jerry Dipoto said in a statement. "His incredible work ethic, preparation and focus will enhance our environment in many ways.
"He's truly one of the great players in the history of the game and his unquestionable presence is a valuable addition, both on the field and in the clubhouse. We're very glad to bring him back home."
Suzuki spent his first 11 major league seasons with the Mariners, earning 2001 AL Rookie of the Year and MVP, winning a pair of batting titles and becoming a 10-time All-Star. He was traded to the New York Yankees midway through 2012, played parts of three seasons with the Yankees, then spent three seasons with the Miami Marlins.
He has a .312 average and 3,080 hits. Suzuki appeared in 136 games last year and hit .255 with a .318 on-base percentage.
The move was necessary for the Mariners after several outfielders have been injured during spring training.
Ben Gamel is sidelined for at least a month with a strained oblique muscle, Mitch Haniger is dealing with a hand injury that has limited his activity for a couple of weeks, and Guillermo Heredia is still in the final stages of recovery from offseason shoulder surgery.
Ichiro is the Mariners' all-time leader in batting average (.322) and hits (2,533). Seattle hasn't reached the postseason since Ichiro's historic rookie season in 2001, when he led the Mariners to a league-record 116 wins in the regular season.
He became a free agent when the Marlins declined his $2 million club option for 2018. The move by the Marlins was the start of an anticipated payroll purge by Derek Jeter's new ownership group. Jeter and Ichiro were Yankees teammates for 2½ seasons.
Ichiro ranks 22nd with 3,080 career hits but started only 22 games last year and had 196 at-bats, the lowest total of his 17-year career. He set a big league mark with 109 plate appearances as a pinch hitter, and had a franchise record 27 pinch-hits.
Ichiro was batting .202 on July 4 but hit .315 the rest of the way. He became just the sixth player 43 or older to record at least 50 hits.
Ichiro, who has said he wants to play until he's 50, was 27 when he began his major league career. He had 1,278 hits while playing nine years in Japan.
The Associated Press contributed to this report.