His Hunger Games: Mockingjay castmate Julianne Moore attended the services at the Church of St. Ignatius Loyola along with Amy Adams, Michelle Williams, Cate Blanchett, Meryl Streep, Mary-Kate Olsen and Justin Theroux.
Philip's longtime partner Mimi O'Donnell and the couple's three children arrived together in a black SUV as 10 pallbearers carried the 46-year-old's casket into the church.
The Oscar-winning actor, who played Head Gamemaker Plutarch Heavensbee in the hit film franchise, died of a heroin overdose on Sunday. He was found dead in his NYC apartment with a needle still in his arm.
Although not all of his Hunger Games costars could be in attendance to say goodbye to their friend, they released a joint statement saying: "Philip was a wonderful person and an exceptional talent, and our hearts are breaking."
While the late actor had completed filming on the majority of his scenes in Mockingjay: Part 1 and 2, he had 7 days of shooting left. He'll reportedly be digitally rendered for one crucial scene that still needs to be shot.