Kojo went before the BGT judges at auditions earlier this year.
Alesha was joined by the panel by fellow judges Amanda Holden, David Walliams and Simon Cowell when Kojo auditioned in the second round of try outs.
"I was not expecting to see you today," Alesha reacted as stand up comedian Kojo walked out on stage.
According to The Sun newspaper, Alesha and Kojo have been pals for over a decade having spent years "regularly attending showbiz events together".
However in an interview with ITV's Lorraine, Kojo played down their connection.
He said: "I don’t have her number.
"I actually know Alesha’s partner, that’s how I know Alesha."
Kojo added: "I don’t even have her number to be like, 'I’m going to be on the show.'
"I literally just went on there, humbled myself. Honestly, this is an opportunity not that I want but I needed to take my little fan base to a whole new level, and to meet people like yourself, and to show the world where I’ve come from."
In his audition episode, after performing a stand up comedy set.
David praised: "You're brilliantly likeable, I think you did yourself really proud today."
Simon then said: "I don't really like comedians on this show... but I loved you!" before hitting the golden buzzer.
Kojo was floored - quite literally - by the buzzer as he lay on stage while golden confetti rained down.
Simon added: "You have the most amazing energy, this is the break you've been waiting for. Enjoy this!"
As it happens, it's not the first Britain's Got Talent golden buzzer Alesha Dixon has had a connection with.
Last year there was controversy when she put Lifford Shillingford through to the live shows after revealing she already knew him.
Playing down their connection at the time, Alesha said: "He’s not a friend, that sounds cold, but I don’t have his phone number.
"I haven’t seen him in years. When I say I know him, I know his music.
"I remember him from back in the day, there were shows that Mis-teeq were doing that he was too. There was just a mutual respect and understanding between us.'
Britain’s Got Talent 2019 airs on ITV.