Houston placed Fiedorowicz, 26, on the Reserve/Retired list, the team announced Thursday.
The No. 65 overall pick in the 2014 NFL Draft, Fiedorowicz is hanging up his spikes after suffering four concussions -- including two that resulted in separate trips to injured reserve last season -- from December of 2016 to December of 2017.
"We have a lot of respect for C.J. and we support his decision to retire," coach Bill O'Brien said in a statement released by the team. "I know this was a difficult decision for him. C.J. has been a great teammate and we appreciate his efforts over the past four years. We wish him success in the next phase of his life."
After recording a career-best 559 yards on 54 receptions in 2016, the former Iowa star earned a $22 million extension with $10.1 million in guarantees at the end of training camp last summer. He will finish his four-year NFL career with 89 catches for 881 yards and six scores.