A young Queensland girl whose father pleaded guilty to giving her cannabis oil to treat her cancer has died just days from her fourth birthday.

Rumer Rose, who can only now be identified, died in her sleep early yesterday morning, her father Adam Koessler, 32, revealed on Facebook, the Brisbane Times reports.

"We are sure that Rumer came to this Earth knowing that she had a monumental battle to fight, and she fought it with everything she had," administrators of the Fearless Father Facebook page wrote.

"No-one could have expected that such a tiny little body could endure so much and still keep fighting back time and time again, but that's exactly what Rumer Rose did.

"Now the time has come for this little warrior princess and her beautiful smile to shine down on us from the stars above."

Rumer was diagnosed with neuroblastoma, a rare form of cancer, in December 2014 and given a 50 percent chance of survival.

On Christmas Day the same year and before traditional medical treatment had begun, Mr Koessler began giving Rumer food cooked in cannabis oil.

When his estranged wife noticed a funny smell in the girl's food she told doctors who informed police, leading to Mr Koesler's arrest outside Brisbane's Lady Cilento Children's Hospital last year.

He was charged with supplying his daughter with a dangerous drug and the media coverage sparked a huge debate about the use of medicinal cannabis in Australia.

After pleading guilty to the charge in March he was fined $500 fine and put on a two-year good behaviour bond.