According to reports, the firefighter died after suffering burns to 70% of his body, bringing the total number of fire-related deaths to five.
A second firefighter was also reportedly seriously injured after suffering burns to 50% of his body.
By Friday morning, the blaze, which has destroyed several hundred homes and saw thousands of residents evacuated, had largely been extinguished.
Nandi Mgwadlamba, a SANParks spokesperson, said on Friday that more than 500 houses had been destroyed and over 7 000 people evacuated.
"Sounds of the Oryx flying over the Knysna estuary, part of the Garden Route National Park, were the first sounds heard this morning," Mgwadlamba said.
"The winds have died down and choppers can now fly to extinguish left-over flames. "All SANParks rangers are assisting to fight the fire," added Paddy Gordon, Park Manager of the Garden Route National Park.
"Our rangers have been at it for the last 48 hours with very little to no sleep." "Our prayers and thoughts go out to colleagues, stakeholders and families whose houses were burnt down."
* Pick n Pay will gather and deliver any online purchases made on their website in aid of Knysna Fire Relief. Click here for more info.