"Been very blessed in my life & career achieve the upmost in boxing, was a [sic] epic journey along the way. Thanks to all the fans that supported & believed in me along the way," he wrote. "Hope you enjoy it as much as I did. THE END."
The 28-year-old, who has an unblemished 25-0 record, became WBA (Super), IBF, WBO and IBO world champion when he defeated Ukrainian Wladimir Klitschko in November 2015 but has not fought since, having pulled out of two planned rematches.
In June 2016 he was charged with doping offences by UK Anti-Doping, allegations he denied.
In October that year, Fury appeared to announce his retirement on twitter, only to then retract the statement shortly before giving up his titles, saying he wanted to focus on dealing with mental health issues.
News that makes sense
Your trusted source for staying up-to-date with the world around you. Get free daily news updates and analysis, straight to your inbox.
The next day, Fury had his licence temporarily withdrawn by the British Boxing Board of Control, a move which his trainer and uncle Peter Fury said could be "a blessing in disguise".
In March 2017, Fury suggested he could make a comeback and when compatriot Anthony Joshua beat Klitschko at Wembley the following month, the new world champion said he wanted to fight Fury, a challenge which Fury accepted on twitter.
(Reporting by Julian Shea; Editing by Ken Ferris)
