Jeffrey de Zwaan started playing darts at the age of eight, and in 2008 he won his very first title at the Leidschendam youth championships. The youngster developed further and started playing LaCo for DSWN (Darts Sport West Netherlands).
Two years after his very first youth title, De Zwaan was invited to the Dutch youth team for the first time. That same year, he made his television debut. Jeffrey was privileged to participate in the Zuiderduin Masters in 2010, where he lost in the first round.
In 2012 De Zwaan won the most prominent youth title, as the Dutchman was crowned winner of the Winmau World Masters. Jeffrey then went on the BDO circuit, where he reached the main tournament of the Zuiderduin Masters and Winmau World Masters.
After two years of playing on the BDO circuit, De Zwaan switched to the PDC in 2015. "The Black Cobra" immediately received his Tour Card on the first day of the Q-School, and in his debut year at the PDC he managed to qualify for the UK Open and the PDC World Championship Darts.
In 2015, Jeffrey threw his first nine-darter with the PDC in a Players Championship tournament. A year later, the Leidschendammer won a tournament on the PDC youth circuit.
In the 2017, De Zwaan qualified for the Grand Slam of Darts and Players Championship Finals.
At the end of 2017, De Zwaan lost his Tour Card, but was quickly able to reclaim it during the Q-School in January 2018, which was to be a breakthrough year for him. De Zwaan reached the finals of a Pro Tour tournament three times, and won his very first PDC ranking tournament that April.
Jeffrey also made a name for himself during the televised tournaments in 2018. He beat Michael van Gerwen at both the UK Open and the World Matchplay. At the World Matchplay, De Zwaan even reached the semi-finals after victories over Adrian Lewis and Dave Chisnall.
In the fall of 2018, "The Black Cobra" was frequently seen on television. Jeffrey made it to the World Grand Prix and Players Championship Finals.
In 2019, De Zwaan lost once again to Rob Cross during the PDC World Championship with his highest TV average ever - 106.09. Three months later he made his debut in the Premier League Darts. He was allowed to fill in for Gary Anderson at Ahoy Rotterdam. His debut match, once again against Rob Cross, was lost 7-4.
In 2020 "The Black Cobra" reached the Last 16 of the PDC World Championship after victories over Darin Young and Dave Chisnall where he equaled his highest TV average - 106.09. During the summer he once again appeared in the Premier League, but is still waiting for his first victory after losing to Peter Wright.
In October 2020, De Zwaan reached the Quarter-Finals of World Grand Prix and reached the Last 16 of the Players Championship Finals.