Mr Aqorau, who until Friday had been a Visiting Fellow at the Australian National University in Canberra for two three-month periods, said the appointment will be effective with the beginning of 2020.
He was CEO of the Parties to the Nauru Agreement, the nine-island tuna cartel, from 2010 to 2016.
During this time, PNA implemented a tuna management programme known as the "Vessel Day Scheme" that reshaped the purse seine industry, generating a huge increase in revenue to participating islands.