The experienced former NRL and Super League boss will take on the role, subject to the approval of his work permit.
Potter, 62, has previously managed Super League teams, including Catalans Dragons, St Helens, and Bradford Bulls.
He led St Helens to the 2009 Grand Final and has also managed NRL clubs Wests Tigers and Canterbury Bulldogs.
In 2017, Potter guided Fiji to the World Cup semi-finals, beating New Zealand on the way.
The former New South Wales representative will now return as the head coach for the Fijian national team, known as the Bati.
Rajesh Singh, Fiji’s National Rugby League chairman, said: “Mick has signed his contract, and we are lodging his work permit application.
“Once that is approved, he will come in and start work full-time.
“He is on a four-year contract, taking us from one World Cup cycle to the next.”
The Fijian side is in Group A for the upcoming World Cup, which will be co-hosted by Australia and Papua New Guinea.
They will face the Cook Islands in Newcastle, followed by a match against world champions Australia in Brisbane, and finally, a clash with New Zealand on the Gold Coast.
Singh further stated: “Mick has provided some names (for his coaching team) and we will discuss those options.
“Ultimately, the head coach will have a major say in selecting his coaching staff.”
In addition to his head coach roles, Potter has been part of the wider coaching team at Newcastle Knights and Parramatta Eels in various roles.