Tim Wakefield will announce his retirement at 5 p.m. ET on Friday.
The long-time Boston Red Sox pitcher, who played for 19 seasons in the majors, will officially call it a day at a news conference at the Red Sox's spring training base at JetBlue Park.
Wakefield, 45, became a free agent at the end of last season, and while he desired a new deal with the Red Sox, it failed to come to fruition.
Knuckleballer Wakefield spent 17 season with the Red Sox. His 186 victories with the team are the thrid most in team history, behind only Cy Young and Roger Clemens, who both had 192. Wakefield was also a part of two World Series-winning teams, in 2004 and 2007.
Last season, Wakefield, the oldest active player in the majors, was 7-8 with a 5.12 ERA in 23 starts.