The contract is worth $12 million and pending a physical. The person spoke on condition of anonymity because there was no official announcement.
The deal was first reported by Fox Sports.
Youkilis is expected to play third base while Alex Rodriguez recovers from hip surgery. A-Rod plans to have the surgery in mid-January and could be sidelined until the All-Star break or beyond.
Youkilis turns 34 in March. He played third base and first base last season for the Boston Red Sox and Chicago White Sox.
Source: Associated Press