The actors posed together for photos with DiCaprio and Pitt both wearing sunglasses.
DiCaprio donned a relaxed blue suit with no tie while Pitt was more casual with a hat and a black long-sleeved shirt.
Pitt and DiCaprio were also joined by their co-star Margot Robbie and the film's director Quentin Tarantino. The group then took questions from reporters about the project which is set to arrive in theaters on July 26.
"It was an incredible ease and comfort getting to work alongside Brad," DiCaprio said. "Brad is not only a terrific actor but he's a professional."
"We together forged hopefully a great cinematic bond in a film about our industry," he continued.
Once Upon a Time in Hollywood is set during the Manson Family murders which took place in 1969. DiCaprio portrays a fictional, fading television star named Rick Dalton with Pitt has his stunt double Cliff Booth. Robbie will star as late, real-life actress Sharon Tate who will be living next door to Dalton. Tate was one of the victims of the Manson Family.
A new trailer for the film was released on Tuesday which features DiCaprio and Pitt's character's trying to stay relevant in Hollywood as the film industry begins to change.
DiCaprio and Pitt mentioned to Esquire on Tuesday how much they enjoyed meeting and working with Perry on the film. Perry, who portrays fictional television actor Scott Lancer in the project, died at the age of 52 in March.
"We were like kids in the candy shop because I remember going to the studios and [Beverly Hills, 90210] was going on and he was that icon of coolness for us teenagers. It was this strange burst of excitement that I had, to be able to act with him," Pitt said.
"Man, he was so incredibly humble and amazing and absolutely committed. He couldn't have been a more friendly, wonderful guy to spend time with. I got to sit down and have some wonderful conversation with him. It was really special," he continued.