Police said the man, believed to be a Public Works Department driver, was trying to cross a river near Labasa on the island of Vanua Levu when he was pulled under by swift currents on Saturday, Radio New Zealand reported.
Fijian disaster management officials said there may have been more fatalities, but communications had been cut to northern and eastern parts of the country making it difficult to confirm the death toll.
Cyclone Tomas was downgraded yesterday after battering parts of Fiji earlier this week, forcing thousands out of their homes into shelter and cutting power and communications.
The Fiji National Disaster Management Office said most people evacuated ahead of the cyclone had now returned home, and all schools had resumed classes, with the exception of six schools in the country's Eastern Division, which were being used as evacuation centres.
Communications had been restored although some parts of the Northern and Eastern districts were still without communications after the Fiji Telecom tower on Taveuni was seriously damaged.
Reconnaissance flights by Australian and New Zealand Air Force Hercules indicated the north and north-eastern areas sustained the most damage from the cyclone, with the level of damage reduced as it moved further south, the Ministry of Foreign Affairs and Trade (MFAT) said.
Yesterday, the New Zealand Hercules transported emergency supplies, including a Red Cross truck, to Labasa before conducting reconnaissance flights over northern Vanua Levu, Taveuni and Rabi.
The Hercules would deliver Ministry of Health, Unicef and Red Cross supplies to Labasa today before returning to Nausori.
The New Zealand Government had promised $1 million in disaster relief for Fiji, matching a similar amount donated by Australia.
Pete North, Habitat for Humanity's New Zealand chief executive, said many houses were destroyed in northern and eastern Fiji and his group had offered assistance in the rebuilding programme.
Habitat had responded to the rebuilding of Samoa after the earthquake and tsunami and was talking with the Cook Islands after the recent cyclone there.
"These Pacific countries are our neighbours and family and we must respond," Mr North said.
Habitat for Humanity and aid agency Caritas were appealing for funds to aid in post-cyclone reconstruction, while other groups including the Red Cross were also appealing for donations.
A natural disaster was declared in Fiji on Tuesday after gusts of wind peaking at more than 200kmh and massive storm surges forced 17,000 people out of their homes temporarily.
A second cyclone, Ului, had hit the Solomon Islands, but no deaths or injuries had been reported.
The storm was likely to cause flooding, crop losses and building damage, MFAT said.
There had been no request for international assistance but New Zealand would help if required.
Around 480 New Zealanders were registered MFAT as being in Fiji, and 60 were registered as being in the Solomon Islands.
