"Justin Thomas is a competitive, aggressive and physical lefthander with an average three pitch mix," said Pirates General Manager Neal Huntington. "With continued development, we feel he could be an interesting option for our bullpen."
Born in Toledo, Ohio, Thomas attended Youngstown State University and helped the Penguins capture a Horizon League Title in 2004, pitching the team into the finals and making its first ever appearance in the College World Series.
Originally selected by Seattle in the fourth round of the 2005 First-Year Player Draft, Thomas made his professional debut with Everett and went on to lead all Seattle farmhands with 14 wins in 2006.
Thomas made his Major League debut with the Mariners in 2008, posting a record of 0-1 and a 6.75 ERA in eight games during the month of September.
Pittsburgh's roster now stands at 39 players, with two players (pitchers Jose Ascanio and Evan Meek) also on the 60-day disabled list.