The sentencing hearing of a 38-year-old fake prince is underway in Brisbane's District Court.

Hohepa Hikairo 'Joel' Morehu-Barlow is set to plead guilty and be sentenced for defrauding the State Government of more than $16 million while working as a middle manager for Queensland Health.

Barlow had explained his lavish lifestyle by claiming to be a Tahitian prince.

The court has heard Barlow was promoted in Queensland Health based on qualifications from a fake law degree.

The hearing continues.