"There was a lot of people who didn't turn up to come and vote because of the weather, so I can understand that," he told Checkpoint.
Opposition parties questioned the transparency of the vote-counting, but the Fijian Election Office rejected this and an interim Multinational Observer Group report called the process credible.
In a statement, Bainimarama lashed out at opposition parties, calling theirs a campaign "based on lies, hate and fear" that spread "baseless fears" about indigenous iTaukei traditional land.
"These same disruptive politicians of old, aided and abetted by the Fiji Times, did not care to tell you the truth – the truth that iTaukei land is not only safe like never before under our Constitution but, as total land holding, has grown under FijiFirst.
"Their lies and deception knew no boundaries, as individuals, whole communities and religious sentiments were slandered and belittled in an atmosphere of political deceit."
Bainimarama called for unity.
"Today I ask all who voted for us, and also those that didn't, to run with us as we all work together to make Fiji a better place."
It is the second time that Fiji has had an election since Bainimarama seized power in a military coup in 2006.
An interim Multinational Observer Group report called the election process transparent and credible - though it noted that the Government was giving out grants during the campaign and would likely comment on that issue for its final report.
But Sodelpa and three opposition parties urged the electoral commission to refrain from officially announcing results, saying the tally process was not transparent.
"The supervisor of elections has been in a great hurry to get the results out," Mahendra Chaudhry of the Fiji Labor Party said in a Facebook Live video, supported by Sodelpa, National Federation Party and Unity Fiji.
"He (the supervisor) has, in the process, compromised the procedures and the requirement of the law, so that should be set right if this election is to have any credibility," Chaudhry said.
Supervisor of Elections Mohammed Saneem rejected any impropriety.
"The Fiji Elections Office is giving all the information accurately in a timely manner," Saneem said in a Facebook Live video.
According to the Fiji Sun, New Zealand's High Commissioner to Fiji Jonathan Curr said he was pleased to see the democratic process in Fiji working.
"My congratulations to the Prime Minister of Fiji, Josaia Voreqe Bainimarama, and the FijiFirst party," he told the Fiji Sun.
"Our bilateral relationship with Fiji is excellent at the moment. I have no doubts that it will continue to be in an excellent shape and will become even better for the next four years."
Fiji went to the polls on Wednesday, but voting was in some parts of the country was pushed back until Saturday due to heavy rain.
Bainimarama campaigned on a continuation of economic growth, political stability and improved social services.
Poverty, however, remains widespread in Fiji and opposition leaders promised to raise the minimum wage.
