The young victim, referred to as 'Ali,' died at the metal band's Alexandra Palace gig on Friday.
Bring Me The Horizon, from Sheffield, were left 'horrified' by the young man's death and expressed their deepest condolences to the victim's family.
The band tweeted: "Words cannot express how horrified we are feeling this evening after hearing about the death of a young man at our show last night.
"Our hearts and deepest condolences go out to his family and loved ones at this terrible time - we will comment further in due course."
Fans responding to the tweet offered their condolences to the victim's family and highlighted the dangers of mosh pits.
Liam Atkins tweeted: "So sad, was at the concert and had no idea, thoughts to family and loved ones - we were all just trying to have a good night out."
Abbi Roberts added: "I know pits are fun but it breaks my heart that people are risking their lives by trying to have fun.
"I was at the gig in Birmingham and people were coming out with bloody noses and visibly broken bones - this is not what music is about."
London Ambulance Service was called to the scene at 9.48pm on Friday when a person was reported unwell at the venue.
A spokesperson said: "We sent an ambulance crew, a paramedic in a fast response car, an advanced paramedic and our hazardous area response team to the scene.
"Our first medic arrived in less than three minutes - sadly the patient died at the scene."
Concert attendee Tina Thorne described paramedics rushing to the scene with an empty wheelchair on Twitter.
She tweeted: "I did see a couple of guys in green running from the back of the venue into the outside part with a wheel chair - no one in it - but obviously on their way to an incident somewhere in the venue."
A spokesperson for Alexandra Palace released a statement on Facebook.
They said: "A medical incident occurred at last night’s Bring Me The Horizon concert.
"Our thoughts and condolences are with the individual's family and we would like to express our deepest sympathy to them.
"We hope you can appreciate we cannot provide any further comment at this time."