The Health Ministry said the trio arrived on a repatriation flight from Auckland on 19 November.
The ministry's Sunil Chandra said two of them were Fiji citizens returning from Mali while the third was a foreign national .
Chandra said the pair had started their journey from Mali while the third patient had transited through New Zealand from Germany.
He said the man worked in Fiji and was returning to the country with his family.
"The first two cases are Fijian citizens, both in their 40s, and worked at a mining company in Mali.
"The third case is a 51-year-old non-Fiji citizen who arrived in Fiji on 19th of November on the same New Zealand flight."
Chandra said as standard procedure for confirmed cases, all three patients had been isolated in hospital.
He said the three patients returned positive results for the coronavirus during tests conducted on day two of their 14-day quarantine.
He said this brings the number of active cases in the country to four.
The earlier case was a 53-year-old man who arrived at Nadi Airport on a repatriation flight from New Zealand on 5 November.
People returning to Fiji go into quarantine for 14 days at a government designated facility supervised by the military.
Fiji has had 38 cases of Covid-19.