The 32-year-old Iowan suffered a setback in his recovery from an injury to his throwing shoulder, which put his 2020 season in jeopardy and prompted the 2011 American League Rookie of the Year to elect retirement.
"Would have had to get surgery and rehab again so decided it was best," Hellickson said.
The Tampa Bay Rays selected Hellickson in the fourth round in 2005, and he made his debut in 2010. He went 13-10 with a 2.95 ERA and 1.15 WHIP over 29 starts the following year en route to earning top rookie honors in the AL.
Hellickson wraps up his career with a 76-75 record over 1,269 1/3 innings with a 4.13 ERA and 1.25 WHIP.