KSI will be fighting Swarmz at O2 Arena in the latter part of the month - a bold hope for a Jake Paul showdown.
YouTuber Alex Wassabi reportedly suffered an injury that forced him to withdraw from the fight with KSI.
KSI has to change his opponent just weeks before the fight
Swarmz, an ex-footballer, has never fought before. He will be the underdog at O2
Swarmz, a rapper who has never fought before, will replace him on August 27,
He is thought to be a friend and colleague of KSI, as the two have known each other through their respective music careers.
After some of his songs became viral in the past few years, Swarmz has a growing career as a musician.
He was a former non-league footballer and had also played for Charlton and Fulham youth academies earlier in his career.
In 2018, he quit the sport to concentrate on his music.
This announcement means that KSI will not be meeting Jake Paul in a much-anticipated bout - despite American calls for it via Twitter.
Paul is embroiled in his own controversy with late fight cancellations, after he pulled the plug on his clash against Hasim Rahman Jr.'s weight.
YouTube star and Youtuber, Jay-Z, took to Twitter to call on KSI for help.
He stated that he heard Alex [Wassabi] was out due to a concussion.
"F***ed up. Alex seized this huge opportunity. Alex will return.
"KSI... Everything happens for a reason.
"I'll fight in your town. Your boxing organization. You are A-Side.
"I also agree that I will pay 180 pounds for August 27. "You accept?"
KSI responded to speculation by tweeting: "We will fight according to my terms, and when we do it, it'll take place on the largest stage."
"I'm talking Wembley stadium fam. A full camp designed just for me and you, so there are no excuses when it comes to fighting. This is not @jakepaul's short notice s***.
Paul replied in capital letters: "This officially is the largest duck of all times."
KSI famously fought Logan Paul, Problem Child's older brother in a 2018 fight, one of the first major fights among Youtube personalities.
Following the draw, they were able to have a professional rematch in Los Angeles in 2019, where KSI defeated Paul in a split decision.
