The deal was agreed to Dec. 23, but the sides had to complete contract language, and the first baseman had to pass a physical.
New York has committed $423.5 million on three free-agent additions during the offseason after its streak of 13 consecutive postseason appearances came to an end. On Dec. 18, the Yankees finalized a $161 million, seven-year contract with left-hander CC Sabathia and an $82.5 million, five-year deal with right-hander A.J. Burnett.
The news conference will be one of the final events at the old Yankee Stadium. The team moves into the new $1.3 billion Yankee Stadium, across 161st Street, next season.