The 34-year-old man was driving on a road in Mindarabin, in Western Australia's Great Southern region, on Tuesday night when he was killed.
The volunteer firefighter suffered critical injuries and died at the scene, police said on Wednesday.
He had earlier been helping firefighters battle a large bushfire in the Shire of Gnowangerup.
Emergency services told people in the area to evacuate on Tuesday and that there was a threat to lives and homes.
For one blaze in the area, the warning advice shifted to "too late to leave" through the afternoon.
The fire has since been downgraded to advice level after burning through more than 5540 hectares.
WA Minister for the Great Southern Reece Whitby labelled the man's death as "enormously tragic".
"Career and volunteer firefighters put their lives on the line every time they attend a fire, and it can be incredibly dangerous out there on the fire front," he said.
"This is incredibly devastating news close to Christmas that we have lost, it appears another person in our Great Southern who is out there involved in a fire operation."
WA Nationals deputy leader Peter Rundle said the death was devastating for the man's family, friends and community.
"The loss of a young volunteer who stepped forward to protect others is profoundly heartbreaking, and it is a stark reminder of the very real risks faced by those who serve on the front line to keep our communities safe," he said.
"Communities are exhausted, hurting and grieving, and the cumulative toll of this fire season is being felt deeply across the region."
The death is the second fire-related fatality in the region after Shire of Ravensthorpe deputy president Mark Mudie died fighting a bushfire threatening his property earlier in December.
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