Many of Hoffman's fellow actors streamed into the Church of St. Ignatius Loyola to pay their respects, including Cate Blanchett, his co-star from "The Talented Mr. Ripley;" Ethan Hawke, co-star from "Before the Devil Knows You're Dead," Amy Adams, co-star from "The Master," Ellen Burstyn, co-star from "Red Dragon;" and Spike Lee, who directed Hoffman in "The 25th Hour."
Hoffman, 46, was found dead in his apartment Sunday of an apparent heroin overdose. He leaves behind his partner of 15 years, Mimi O'Donnell, and their three children.
Playwright David Bar Katz, who found Hoffman's body, was visibly upset as he arrived.
The actor's body was carried into the church by pallbearers, as O'Donnell followed, holding their youngest child.
Meryl Streep, Michelle Williams, Julianne Moore, Joaquin Phoenix, Louis C.K., Mary Louise Parker, John Slattery, Jerry Stiller, Marisa Tomei, Diane Sawyer and her director husband, Mike Nichols were also in attendance.
The Church of St. Ignatius Loyola is the church that hosted the funerals of Jacqueline Kennedy Onassis, Lena Horne and Aaliyah.
A larger memorial service is being planned for later this month.
While Hoffman was found with a syringe in his arm and dozens of bags of heroin in his apartment, a medical examiner's office is awaiting toxicology tests to determine the official cause of death.
As the investigation into Hoffman's death continues, three people have been arraigned on drug charges, including one who is facing a felony charge of heroin possession with intent to sell. Lawyers for the three people charged vigorously denied their clients had any role in Hoffman's death.
The Associated Press contributed to this report.