The Manchester fight will take place at the AO Arena on 14 October.
KSI, real name Olajide Olatunji, has admitted it will be “the toughest fight in the influencer boxing scene”.
He has previously fought Jake Paul’s brother Logan, another YouTuber, who will fight at the same event against an unannounced opponent set to be revealed in the coming days.
“I’m used to growing up fighting against proper boxers.”
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February: Scuffles at Fury and Paul weigh-in
Fight won’t be professionally sanctioned
KSI, who first rose to fame playing the FIFA video game for an online audience, is a regular on the popular Sidemen YouTube channel, which has nearly 19 million subscribers.
October’s fight is being organised by his Misfits Boxing label and will be broadcast by DAZN.
However, the fight has not been sanctioned by the British boxing regulator as a professional match – and KSI lacks a professional licence in the UK.
Only one of his previous fights has been professionally sanctioned, with the others all exhibitions.
His bout with Fury has instead been sanctioned by the Professional Boxing Association, but it won’t count towards either fighter’s professional record.