On 22 June 2017, Ntilikina was selected by the New York Knicks with the eighth pick in the 2017 NBA draft. On 5 July, Ntilikina signed with the Knicks. He was the second youngest active player in the NBA during his rookie year behind Ike Anigbogu. Ntilikina made his NBA debut on 19 October 2017, in a blowout loss to the Oklahoma City Thunder. He scored his first points on 28 October against the Brooklyn Nets in a 107–86 blowout win. He recorded 9 points, 2 rebounds, 5 assists and a steal during the Knicks' home opener. On 15 January 2018, Ntilikina recorded his first double double with 10 points, 10 assists, 7 rebounds, 2 blocks, and a steal in a 119–104 win over the Brooklyn Nets. On 24 January 2018, he was selected to represent Team World for the Rising Stars Challenge during the 2018 NBA All-Star Weekend. His rookie season in New York was considered by many as underwhelming, and was often claimed to be a draft bust. He was limited to 43 games in his second season due to injuries. Heading into his third season, Ntilikina was coming off a strong performance in the 2019 FIBA Basketball World Cup. In the early part of the season, Ntilikina took over starting point guard duties and began to show great signs of defense. On 23 November 2019, Ntilikina racked up 6 steals in a 111–104 loss to San Antonio Spurs. However, like his previous two seasons, he struggled to shoot the ball and eventually was demoted in favor of Elfrid Payton.