Dominican Republic newspaper El Caribe first reported the deal and says Cruz will sign a four-year, $57 million contract. ESPN.com's Jerry Crasnick confirmed that Cruz had agreed to a multiyear deal with the Mariners.
In 2014, his only season with the Baltimore Orioles, Cruz led the major leagues with 40 home runs and was named an All-Star.
He hit .271 and drove in 108 runs, which was third in the American League, helping Baltimore win the American League East and advance to the ALCS, where it was swept by the Kansas City Royals.
Cruz, 34, played 72 games in the outfield and 95 at DH last season.
He rejected a one-year, $15.3 million qualifying offer last month from Baltimore after making $8 million last season.
ESPN reported the Orioles offered Cruz a three-year deal before free agency. Cruz indicated during the season he was interested in staying with the team.
Cruz spent his first eight MLB seasons with the Texas Rangers. He was suspended for 50 games in August 2013 for his ties to the Biogenesis clinic, which allegedly provided performance enhancing drugs to MLB players.
In nine MLB seasons, Cruz, a three-time All-Star, is a .268 hitter with 197 home runs and 597 RBI.
- Scooby Axson