According to ESPN.com, Atchison will earn $420,000 next season, and the club options are for $440,000 and $600,000, respectively.
Atchison, who spent the past two seasons in Japan, last pitched in the U.S. while in the Giants' organization in 2007. That year, the 33-year-old right-hander posted a 4.11 ERA in 22 games for the Major League club along with a 2.01 ERA in 38 games for Triple-A Fresno.
Mainly a fastball/slider pitcher, Atchison signed a Minor League contract with the Red Sox after that season, but the club sold his rights to the Hanshin Tigers in January 2008.
"He's a guy we signed to a Minor League contract a couple years ago, and we liked him, but he ended up having an opportunity to make a lot of money this year in Japan, and it turned out he wanted to come back, so we had a relationship, and had a dialogue, from a couple years ago, so it came together pretty quickly," said Red Sox general manager Theo Epstein.
During his two seasons in Hanshin, Atchison sported a combined 2.77 ERA while striking out 81 and walking 20 in 194 2/3 innings.
Can that success carry over in the Majors?
"I think it can help," said Epstein. "Pitching, especially, is a lot about confidence, and he's done really well over there. Obviously, it's a really high level of competition. He didn't get the opportunity over here to pitch at the highest level, so now he got the opportunity to be a dependable setup guy over there. We'll see if he can come back and translate some of that success over here. We like him. He's definitely an option for us. He can come here, show up to Spring Training and try to win a job."
Originally drafted by the Mariners in the 49th round in 1998, Atchison has a 4.10 ERA in 53 relief appearances spanning three Major League seasons.