He’s their biggest fan.

Timothee Chalamet might as well be an honorary Knick at this point. The “Marty Supreme” star partied with the players at the Seville in New York on Monday night and it felt like “he’s a part of the team,” a spy told Page Six.

“He was so friendly with the players, so happy… dancing and hanging out with everybody. It was like he’s a teammate. They were so engaged,” they added.

Chalamet arrived to the party solo and we’re told he was in “very high spirits,” hanging out with Jalen Brunson, Karl Anthony-Towns, OG Anunoby, Mohamed Diawara, Josh Hart and other players. “He was elated,” the source said of Chalamet.

The evening also brought out Kit Harrington, Jim Jones, Fabolous, A Boogie wit da Hoodie, Ciara and Russel Wilson. Guests noshed on food served by Scarpetta, and were treated to performances by A$AP Ferg and Fetty Wap.

We hear the young players teased LDV Hospitality’s John Meadow, who hosted the party, by referring to him as “sir.” A highlight of the evening was when the champions received custom Don Julio 1942 bottles inscribed to commemorate their historic win, we’re told.

It’s been nonstop celebrating for the players since they defeated the San Antonio Spurs and made history by winning their first championship since 1973. On Sunday, David Rodolitz opened his private members spot, Flyfish Club, to host a victory party for the NBA stars, where they raged until 3 a.m.

“All the players were in tremendous spirits [and] high energy,” Rodolitz exclusively told Page Six. “There was a lot of chemistry with these guys — like, the natural chemistry and the way they move on the court, it continued at Flyfish Club. It was collaborative. There was so much love and fun and joy.”

Trey Jemison III and Kevin McCullar Jr., were spotted celebrating with their wives and girlfriends at Sushi by Boū’s Times Square location. Perhaps Chalamet recommended it. (He and Kylie Jenner had a double date at its Lower East Side location last month).

The players’ party at Seville wrapped at around 3:30 a.m., giving them plenty of time to rest up before Thursday’s big parade.