The 35-year-old Pineiro last pitched in the majors with the Los Angeles Angels in 2011. He played winter ball in Puerto Rico looking for a chance to make a major league roster.
Pineiro, who has a 4.41 ERA in 335 major league games, spent seven seasons with the Seattle Mariners, and won a career-best 16 games to go along with a 3.78 ERA in 2003. He has also pitched for the Boston Red Sox and St. Louis Cardinals.
He will report to extended spring training in Mesa.