Niko Kari started karting in 2009 partaking in many championships across Finland, such as winning the Finnish KF6 Challenge and 13th in Finnish Championship – KF3. In 2014, he moved to Europe to compete there.
Kari made his step up to single seaters in SMP Formula 4, driving for Koiranen Grand Prix. With 7 wins and 19 podiums under his name, Niko easily dominated the SMP championship, winning it with 153 more points than second place, Vladimir Atoev.
For 2016, he moved to the Formula 3 European Championship, driving for Motopark, alongside Sérgio Sette Câmara, Joel Eriksson and Guanyu Zhou. Also with Motopark, he competed in Masters of Formula 3. At this time, he was announced to be joining the Red Bull Junior Programme, where he remained until 2017.
For the following 3 years, he competed in GP3: 2016, 26th with Koiranen GP; 2017, 10th with Arden; 2018, 17th with MP Motorsport.
In 2018, he replaced Ralph Boschung in the final two rounds of Formula 2 in Sochi and Yas Marina, where he retired 3 out of the 4 races he competed in.
For 2019, he joined the newly combined series, Formula 3, competing with Trident, driving alongside Devlin DeFrancesco and Pedro Piquet. Also during this year, he competed in Formula Regional European with KIC Motorsport during the Monza round. Despite only racing 3 races, he scored 26 points, putting him in 15th ahead of Joey Mawson.
FIA Formula 3 Championship
Niko originally made his Formula 3 debut in the Formula 3 European Championship with Motopark. Out of the 30 races he competed in, he won one and was on the podium 5 times. This gave him 129 points, placing him 10th in the standings behind Ben Barnicoat. Kari was also entered into the Masters of Formula 3 race, where he qualified 4th and finished 3rd in the qualifying race. In the main race, he finished in 2nd, behind teammate Joel Eriksson. He also made his GP3 debut with Koiranen GP, replacing Ralph Boschung for a round. He retired in race 1 and finished 14th in the second race. Despite this, the championships he raced in gave him the entrance to the Red Bull Junior Programme along with Sérgio Sette Câmara.
Kari then made his proper GP3 debut season with Arden International, racing for the entire season. For the 15 races, he scored a win and 2 podiums and 7 points-finishing positions. This meant he had 63 points, classifying him in the standings at 10th ahead Dan Ticktum.
For the following season, he was driving for MP Motorsport in the GP3 series. Niko drove for 7 rounds, achieving 6 points, though he was promoted after Monza to drive on Formula 2. He finished 17th in the standings Columbian Tatiana Calderón.
With Formula 3 European joining with GP3 to create Formula 3, he moved to Trident, driving with Devlin DeFrancesco and Pedro Piquet. In the 16 races, he achieved 2 podiums. One was in Circuit de Barcelona-Catalunya and the other at Sochi Autodrom. He ended the season on 36 points, putting him in 12th behind MP Motorsport driver, Liam Lawson.
For the 2020 season, he was announced to be driving with Charouz Racing System, alongside Federico Malvestiti and Matteo Nannini.