One of A's general manager Billy Beane's priorities this offseason was to find a reliable hitter who can help the club score more runs for its talented pitching staff.
The 36-year-old Matsui hit .274 with 21 home runs and 84 RBIs with the Angels last season, his first season in Anaheim after seven seasons with the New York Yankees.
Manager Bob Geren was forced to mix and match in the designated hitter spot after six-time Gold Glove third baseman Eric Chavez wound up injured yet again and played in only 33 games. Jack Cust, who played 88 games at DH in 2010, signed last week with the Seattle Mariners.
The A's stayed in the AL West chase until late in the season -- losing out to the AL champion Texas Rangers -- and finished 81-81 for second place in the division. That was despite using the disabled list 23 times, two fewer than the franchise record set in 2008.
In addition to Matsui, the A's also signed 27-year-old right-hander Brandon McCarthy to a one-year deal.
McCarthy did not pitch in the majors last season and was limited in Triple-A with a stress fracture in his shoulder. He is 20-24 with a 4.56 ERA in five major league seasons with the Chicago White Sox and Rangers.
The A's also said they have agreed to terms with right-hander Joey Devine on a one-year contract worth $557,500, leaving five players eligible for arbitration: Dallas Braden, Craig Breslow, Conor Jackson, Kevin Kouzmanoff and Brad Ziegler.
Last week, Oakland failed to reach agreement on a contract with Japanese pitcher Hisashi Iwakuma during the allotted 30-day negotiating period.
Devine missed the past two seasons recovering from reconstructive Tommy John elbow surgery in April 2009. He last pitched in the majors in 2008, going 6-1 with a 0.59 ERA in 42 relief appearances for Oakland.
Buster Olney covers Major League Baseball for ESPN The Magazine. Information from The Associated Press was used in this report.