Sandoval signed a reported five-year, $95 million deal with the Red Sox, with a $17 million sixth-year club option. He spent the first seven years of his career with the San Francisco Giants, winning three World Series there.
"I want a new challenge. I need a new challenge," he said. "I know that I had a great career in San Francisco. But I'm going to have a new one here."
The Red Sox also announced an agreement to sign shortstop Hanley Ramirez on Tuesday, whom the team called a leftfielder in its introduction. Ramirez's deal is for four-years and worth a reported $88 million.
Sandoval said he, Ramirez and Red Sox designated hitter David Ortiz are already being called "Three Amigos" and said he's excited to play with both players.
Sandoval hit .279 with 16 homers, 73 RBI and a .739 OPS in 157 games last season. A two-time All-Star, the 28-year-old has a lifetime .294 average with 106 home runs and 462 RBI.
One year after winning the World Series, Boston finished 71-91 in 2014 and in last place in the AL East.
- Molly Geary