The 34-year-old right-hander agreed Thursday to a $1.25 million, one-year contract after Seattle released veteran starters Randy Wolf and Scott Baker this week. Young can earn an additional $3,475,000 in roster and performance bonuses and would get the full amount if he makes 28 starts and pitches 180 innings.
Young has not pitched in the majors since 2012, but Seattle is taking a chance he can be a serviceable starter behind Felix Hernandez, Erasmo Ramirez and James Paxton until Hisashi Iwakuma and Taijuan Walker return from injuries.
Young allowed four earned runs over 10 1-3 innings in two spring training starts with Washington, which released him Tuesday.
At 6-foot-10, Young is tied for the second-tallest player in major league history. The Princeton graduate spent last season in the Nationals' minor league system as he struggled with troubles in his pitching shoulder, and he was 1-2 with a 7.88 ERA in seven starts at Triple-A Syracuse.
An All-Star in 2007, Young has a 53-43 record and 3.79 ERA in nine major league seasons with Texas (2004-05), San Diego (2006-10) and the New York Mets (2011-12).
Young would get $125,000 bonuses for 30 and 60 days on the active roster and $75,000 for 45. He can earn $150,000 each for 60, 80, 90, 110 and 125 innings; $200,000 apiece for 140 and 155; and $250,000 each for 170 and 180. He also would get $150,000 each for 12, 15, 18 and 20 starts; $200,000 apiece for 22 and 24; and $250,000 each for 26 and 28.
Seattle believed it had the veteran it wanted in the rotation with Wolf. But he declined to sign a 45-day advanced consent waiver earlier this week and instead asked for his release. The waiver would have allowed Seattle to pay him only a prorated portion of his contract if he was released within the first 45 days of the regular season.
Iwakuma (finger) and Walker (shoulder) are not expected to be available to join the Mariners rotation until mid- to late-April at the earliest.
Left-handed reliever Bobby LaFromboise was designated for assignment to clear a spot for Young on the 40-man roster.