Although Harrison retires with a professional record of 31 wins and seven defeats, he was unable to translate his success as an amateur - which included the Olympic and Commonwealth Games gold medals - to the paid ranks. He captured the European heavyweight title and fought fellow Londoner David Haye for a world title in 2010, when he was stopped inside three rounds.
Harrison was knocked down in 70 seconds by Deontay Wilder in April 2013 and immediately announced he was quitting, yet 48 hours later said he would fight on until he had a heavyweight world title.
However, Britain's first fighter to win Olympic gold in the heaviest weight category has not fought since, despite hints on social media that he would resume his career.
Harrison is walking away from boxing while he still can
Elsewhere, it was confirmed on Thursday that James DeGale will fight for the International Boxing Federation super-middleweight title against Andre Dirrell on May 23 in Boston.
Dirrell's camp won the purse bids to stage the clash for the vacant crown, which was vacated by Carl Froch, in the United States, and they have opted for Boston.
Unlike heavyweight Harrison, there is every prospect that DeGale could become the first Olympic gold medallist to claim a world title. But DeGale will be stretched by the slippery American, whose only defeat was a split-decision defeat by Froch in 2009.
"Dirrell's only lost the one fight to Froch where a lot of people thought he'd won, but it's my destiny and my time to become a world champion," DeGale, from Willesden, London, who once attended a ballet school, said on Thursday.
Nicola Adams's hopes of making a successful defence of her Olympic title in Rio next year could rest on a potential showdown with domestic rival Lisa Whiteside in Liverpool next month. Adams and Whiteside have both confirmed entries in the flyweight division at the English national http://issuu.com/tastefulquiet1030/docs/14275395905516868675a29
