Domestic-made Bluebottle vessels will be gifted as part of a strengthened military partnership between the two countries.
The drones can provide reconnaissance and surveillance and can stay at sea for more than 180 days, powered by renewable energy.
Giving more detail, particularly about the number of drones being supplied would "tip off drug smugglers", Defence Industry Minister Pat Conroy said.
"The beauty of them is that they're quiet. They're literally powered by the sun, the waves and the wind," he told reporters.
"They are virtually impossible to detect unless you get very close to them, so that gives us a real operational advantage."
The drones will be given to Fiji as part of the Waqa Moana partnership, a Pacific-led security initiative to counter organised crime and drug trafficking in the region.
Australia pledged $600 million at the Pacific Islands Forum in September to help implement the partnership.
It follows Australia and Fiji signing the Ocean of Peace Treaty in July, which is a mutual defence pact. Just hours after that deal was struck, China conducted a ballistic missile test in the South Pacific.
It was just the fourth alliance Australia has signed - the others being with the US, New Zealand and Papua New Guinea. It is Fiji's first.
The Bluebottle partnership coincides with the opening of a manufacturing hub in Sydney for Ocius, the makers of the Bluebottles.
The federal government in March signed a $176 million agreement to buy 40 more of the maritime drones for the navy, bringing the total in the fleet to 55.
Bluebottles have been used by the navy from the HMAS Coonawarra in Darwin as part of border security measures.
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