The De Hood Boxing Centre has given hundreds of youngsters a fighting chance of a better future since opening its doors in the troubled area of Manor Top six years ago.
The facility - which has 1500 members aged six to 84 - has won praise from police for reducing crime by giving youngsters discipline and focus.
But the venue faces an uncertain future as it is claimed Costa Coffee and the Iceland supermarket chain have expressed an interest in building outlets on the site.
The centre is based in a former school building owned by the council and there is concern that the building could be demolished to make way for the new retail developments.
More than 3000 people have now backed an online petition which has been launched in a desperate bid to help secure its future.
Reagan Denton, who launched the centre after turning his own life around after a stint in prison, said: "This was built in The Manor, by The Manor and for The Manor and it has got to stay.
"It saves lives and has transformed the community. Who would kick those kids out of that centre?
"We want to work with the council to find a solution and we want to secure our future here."
The 39-year-old once held high ambitions for a glittering professional boxing career but readily admits he ended up in the 'wrong crowd' and served a two-and-a-half-year prison sentence for criminal damage.
Upon his release, he set about changing the area that he was born and bread in after witnessing youths going down the same wrong path that he did.
The centre is now used six days a week by visitors for boxing, football, basketball, boot camp and weight loss sessions. There is also a drop-in called 'Kick Back Recovery' for people with drug and alcohol problems.
It is based within the former Prince Edward School building in Prince of Wales Road. The council owns the building and has let De Hood use it for free since 2015 as they act as caretakers keeping the site in good condition.
But with talk of future plans for the site Reagan and fellow gym users are campaigning to secure a long term lease of at least 10 years from the council.
They are also asking the authority to designate the building as an 'Asset of Community Value' - which would afford it additional protection by law from redevelopment.
Reagan said that if the building ultimately does make way for redevelopment, then the boxing centre must be given a new home close by.
He added: "Things are a bit up in the air but we are confident it will have a future.
"We are doing great things and want it to grow together."
Reagan plans to speak at the full council meeting on March 28 to put their case forward.
A spokesperson for Sheffield Council said no formal planning application has been submitted yet.
He said he could not comment further at this stage but there should be updates within the next few days.
Costa Coffee and Iceland have been contacted for comment and we are awaiting a replies.