Aoki, who turns 34 in January, played with the Giants this past season. He finished the year with a line of .287/.353/.380 with five home runs, 26 RBI, and 14 stolen bases in 392 plate appearances. He last started a game on August 31, making only two pinch-hit appearances in early September before the Giants shut him down for the remainder of the season due to lingering concussion symptoms after being hit in the head with a pitch.
He had a $5.5 million option for 2016 which the Giants declined in early November. The terms of the Mariners deal are not yet known.