The deal includes an invitation to big league spring training, team spokeswoman Pam Ganley said Tuesday.
Reyes was 3-1 with a 3.55 ERA in 59 appearances last year with the St. Louis Cardinals, his 10th major league team. The 33-year-old has pitched in at least 50 games in each of the past five seasons and is 35-35 with a 4.18 ERA in 669 career outings.
Boston has been trying to improve its bullpen, which had the AL's third worst ERA last year. The Red Sox have added right-handers Bobby Jenks, Dan Wheeler and Matt Albers and re-signed lefty Hideki Okajima.
The team has also signed right-hander Alfredo Aceves to a major league contract, a source told ESPN The Magazine's Buster Olney.
Aceves' deal is worth $650,000, with $200,000 guaranteed and another $100,000 due to incentives, according to the source.
The 29-year-old Aceves is 14-1 with a 3.21 ERA in 59 appearances
over three seasons, all with the New York Yankees. He was 10-1 with
a 3.54 ERA in 2009. He pitched only 12 innings in 10 games last
season before going on the disabled list May 9 for the rest of the
season with a back injury. He was 3-0 with a 3.00 ERA.
On Nov. 30, Aceves had surgery after breaking his left
collarbone in a bicycle accident in Mexico. At the time of the
operation, the Yankees said he would need three months of
Information from The Associated Press contributed to this report.