The 44-year-old has spent the last three seasons with the Miami Marlins.
If a job in the majors had not opened up, he was planning to play in Japan for the 2018 season.
The news follows a six-day absence by starting RF Mitch Haniger, who is dealing with hand tendinitis that inhibits his swing.
Gamel, 25, is in line for regular at-bats with the 2018 Mariners after posting a solid.275/.322/.413 slash with 11 homers, 27 doubles and five triples through 550 plate appearances past year in his first full big league season.
Numerous free agent outfielders are unsigned, including Melky Cabrera, 33, but they are likely seeking more than one-year deals.
The Mariners had high hopes for Gamel this season after posting a.275 batting average with 59 RBI's a year ago.
Suzuki started his big-league career with the Mariners in 2001 following an immensely successful nine-year stint with the Orix BlueWave (now Buffaloes) of Nippon Professional Baseball's (NPB) Pacific League. Last season he hit a dismal.255/.318/.332 for just 50 hits and 17 walks in 215 plate appearances. A 10-time All-Star and 10-time Gold Glove victor, Ichiro holds the record for hits in a season with 262 and has had 10 200-hit seasons during his career. Heredia recently made his spring debut and has had a couple of at-bats, but he's more of a depth piece and fourth outfielder than an everyday option (though he could handle left field on a short-term basis with Gamel out).