Penny reportedly isn't the only pitcher at Blue Jays camp that decided to retire on Friday. According to multiple reports, veteran reliever Rafael Soriano also is walking away from baseball.
Manager John Gibbons said Penny, a 37-year-old right-hander, informed him on Friday.
A two-time All-Star, Penny was in Toronto's spring training camp after signing a minor league contract in December. He had a 10.29 ERA in four exhibition appearances, giving up five runs in two innings during his lone start against a Houston Astros split squad on Thursday.
Penny, part of World Series-winning teams with the Marlins in 2003 and the Giants in 2012, had not pitched in the majors since September 2014 with Miami, where he posted a 6.58 ERA in eight outings.
Penny spent 14 years with the Marlins, Dodgers, Red Sox, Giants, Cardinals and Tigers. The veteran also pitched one season for the Fukuoka SoftBank Hawks of Nippon Professional Baseball in Japan in 2012.
Soriano, a former All-Star closer, had signed a minor league contract with Toronto last month.
The 36-year-old Soriano pitched six games for the Chicago Cubs last July after signing as a free agent, going 2-0 with a 6.35 ERA. His last full season came in 2014 with the Washington Nationals.
An All-Star with Tampa Bay in 2010, Soriano ranks eighth among active pitchers with 207 saves. He has also spent time with the Seattle Mariners, Atlanta Braves and New York Yankees over 14 big league seasons.
The Associated Press contributed to this report.