Tom Bell, from Doncaster, was described as an "outstanding" talent and a "considerate human being".
Originally posted by BBC
Tom Bell was shot at the Maple Tree in Woodfield Way, Doncaster, on Thursday evening and died after being taken to hospital.
James Harrington, his coach as a professional, said: "Tom had his full life ahead of him, he would have been the very best out there."
South Yorkshire Police said investigations were ongoing and appealed for witnesses to contact them.
No-one else was hurt in the attack and no arrests have been made.
Side fact about Bell: As Edwin Valero died undefeated with a 100% KO ratio, Tom Bell died undefeated with a 0% KO ratio, and I believe he is the only undefeated fighter to have a 0% KO ratio.