The 21-year-old fled the Sunshine Coast blaze with another woman and was helped by neighbours before being taken to hospital.
However she succumbed to her injuries as police declared a crime scene at the Buderim site, with authorities yet to determine the cause of the fire.
Emergency services were called to the King Street address about 7:30pm on Sunday, following reports one of the complex's units was fully engulfed in flames.
The 21-year-old woman from Kallangur, north of Brisbane, escaped but suffered serious burns, police said.
A 32-year-old woman was able to flee the fire uninjured.
Residents of neighbouring units were evacuated as the fire engulfed the unit located near a service station.
They were allowed to return after fire crews took about an hour to extinguish the blaze, police said.
Police were unable to confirm reports a dog was also in the unit.
An investigation into the blaze was in its early stages, Detective Senior Constable Robert Lowry said.
"We are speaking to people and they are assisting us with our inquiries," he told reporters at Maroochydore on Monday.
"We are putting a call out to the community if anyone has any information to come forward.
"Everything is in our scope at the moment for lines of inquiry."
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