The Dockers utility informed his teammates on Wednesday that his body could no longer cope with the rigours of AFL football.
The 28-year-old has not played for Fremantle since he ruptured the anterior cruciate ligament in his right knee in round five last season.
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Following a full reconstruction, Bradley signed a one-year deal to remain at Fremantle in 2014 but he has been plagued by recurring hamstring issues that are a direct result of the knee reconstruction.
He has played 11 matches in the WAFL this season but has failed to break into the Fremantle line-up. Bradley told the club's website that the decision to retire was fairly straightforward.
"I'm nearly 29 now and I haven't really played in the past two years after my knee reconstruction," Bradley said.
"I've tried to come back this year as soon as my body would let me, but I've done about five hamstrings on the way. Just with the pace of the game now, how fast it is, it looks like the game has gone past me.
"I played WAFL on the weekend and my body was a bit sore. That was the final nail in the coffin that it wasn't meant to be.
"I'm going to have a couple of months off. The body is a bit sore and the hamstrings are hanging by a thread.
"Hopefully I'll stay in footy in some shape or form. I've enjoyed my time down at Peel trying to develop some of the young guys and hopefully fast track them."
Bradley will play the last two WAFL matches of the season and, barring an unlikely call-up to the senior side, will finish on 117 AFL matches. He played 49 with Essendon after he was drafted with pick No.6 in the 2003 NAB AFL draft.
Bradley joined Fremantle in 2008 and played a further 68 games for the Dockers.
