Niinisto was re-elected for the second six-year term in the first round of elections, collecting more than 62 percent of the vote.
"Niinisto has clearly won this race, my warm congratulations to him", Haavisto, the Greens of Finland candidate and Niinisto's closest rival, told reporters.
None of the other six candidates received more than 7 percent of the vote.More news: Z Calls Donald Trump a 'Superbug,' Trump Responds
But the closest competition for President Niinisto came from Pekka Haavisto, a gay, left-wing Green who reached a second round against Mr. Niinisto in 2012 - a campaign that enchanted liberal-minded celebrities and electrified younger voters, especially in Helsinki.
Born into a working-class family in the south-western Finnish town of Salo in August 1948, Niinisto - the youngest of four children - became a lawyer before entering politics as a member of the conservative National Coalition Party.
Niinisto, 69, needed a majority of Sunday's vote to prevent a runoff and win outright. Some political observers suggested that Mr. Haavisto was running with an eye on the 2024 election, reluctant to challenge Mr. Niinisto head on because of the incumbent's popularity after a largely error-free first term.More news: Padmaavat box-office collection Day 2: Sanjay Leela Bhansali's film exceeds expectations
Eurosceptic politicians, Laura Huhtasaari from the nationalist Finns Party and independent Paavo Vayrynen, won 6.9 percent and 6.2 percent of votes, respectively.
The politician who campaigned as an independent, has skilfully shifted the European Union member state closer to North Atlantic Treaty Organisation without antagonising Russian Federation, with whom the Nordic nation shares the longest border in the bloc.
In these elections, Niinisto ran as an independent with no association to the NCP that he earlier chaired.More news: President Moon congratulates tennis sensation Chung Hyeon