"He's a veteran presence and a tremendous leader by example," general manager Neal Huntington said.
Mientkiewicz has a .271 batting average (814-for-3009) with 201 doubles, 64 home runs and 372 RBI in 942 games in the big leagues with Minnesota, Boston, the New York Mets, Kansas City and the New York Yankees.
After breaking into the major leagues in 1998 with the Twins, Mientkiewicz led all American League first basemen with a .997 fielding percentage in 1999. He also earned a Rawlings Gold Glove at first base during the 2001 campaign and ranks second all-time among first basemen with a .996 career fielding percentage (minimum 500 games).
The Pirates now have a total of 66 players scheduled to participate in big league camp.