The firefighter injured while battling a blaze in the Lower Hutt suburb of Petone on Friday has been transferred to the National Burns Unit in Auckland for further treatment.
More than a dozen fire engines and over 60 firefighters attended the fire which is believed to have started in the back room of a building owned by auto upholstery company Racetech.
One of the firefighters suffered serious burns to his back and arms.
At the height of the blaze, plumes of smoke scattered the city and the Fire Service advised people to stay indoors due to possible toxic chemicals in the fumes.
Wellington region fire service commander Ian Pickard says it is very rare for a firefighter to be injured on duty.
He says the thoughts of colleagues from around the country are with the injured man and his family.
A review is underway looking at how the firefighter was hurt and fire investigators remained at the scene on Saturday morning trying to determine the cause of the blaze.