Hereford & Worcester Fire and Rescue Service (HWFRS) was called to a property in Falcon Lane in Ledbury just before 1.30pm yesterday (Sunday 30 December) to reports of a person on fire.
Two crews from Ledbury attended, joining police and ambulance staff at the address.
Station Commander Martin Lown from HWFRS said: "Crews arrived at the property to find a casualty being treated for severe burns believed to have been caused by a fire ball from an out-of-control garden bonfire.
"Due to the extent of the man's injuries, he was flown by air ambulance to the Queen Elizabeth Hospital in Birmingham for treatment and he remains in hospital this morning in a critical but stable condition."
Confirming that firefighters extinguished the bonfire and that fire investigation officers are looking to establish exactly how the man's injuries were caused, he added: "The fire is being treated as accidental but it highlights the need to take extreme care if lighting a bonfire in your garden."
He reminded people to light fires in a suitable spot well away from the house, wooden fences or sheds, and to burn only natural materials. Never dispose of hazardous items such as aerosol cans, spent fireworks, dry cell batteries or flammable liquids on a bonfire.