Bart Nieuwkoop (born 7 March 1996) is a Dutch professional footballer who plays as a right back for Dutch Eredivisie club Feyenoord.
Nieuwkoop is a youth exponent from Feyenoord. He made his team debut on 4 October 2015 against De Graafschap starting in the first eleven and was replaced after 68 minutes by Tonny Vilhena.
On 30 April 2021, it was announced that Nieuwkoop had signed a three-year contract with Union Saint-Gilloise, recently promoted to the Belgian First Division A.