Thorburn killed Tiahleigh Palmer and dumped her body in a Gold Coast river in 2015 in what was described as a cold and calculated crime.
Queensland Corrective Services on Saturday confirmed a 64-year-old man had died at Woodford Correctional Centre overnight.
He was found unresponsive in a single cell around 10pm and efforts to revive him were unsuccessful.
"The incident has been reported to police and (corrective services) will assist with their investigation," a statement from corrective services said.
"All deaths in custody in Queensland are referred to the coroner."
Thorburn had previously been found unresponsive in his jail cell, most recently in 2022 when he was rushed to Princess Alexandra Hospital.
He was 57 when he pleaded guilty in 2018 to charges of murder, perjury, interfering with a corpse and attempting to pervert the course of justice.
He was sentenced to life in jail and wouldn't have been eligible for parole until 2036.
Tiahleigh's murder was described as "cold, calculating and callous" by the sentencing judge.
The court was told Thorburn killed her after learning his son Trent had sex with her and feared she was pregnant.
Thorburn's wife and Trent were also jailed for their involvement in Tiahleigh's death.
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