The pair, who co-star in the new film The Irishman, discussed their friendship and rise to fame during Wednesday's episode of Today.
De Niro and Pacino previously co-starred in The Godfather Part II, Heat and other films. Host Harry Smith asked De Niro to name what he most admires about Pacino.
"We've sort of grown up over the years, decades, and had similar types of situations in our lives -- success and this," De Niro said.
Pacino agreed they had a similar trajectory in their careers and similar experiences with fame.
"We both sort of happened around the same time," Pacino said. "Maybe it was to the era -- back then, it was a different thing being famous."
"And we were suddenly famous, even though we had been working for years before," he added. "I think that has a way of affecting you, and somewhere, somehow we knew it," he added.
Romano, who appeared on Today with De Niro and Pacino, said The Irishman is a great movie to see in theaters.
"If any movie is an argument for keeping the theater experience alive, it's this type of movie," the actor said. "To be on the big screen, with an audience, to feel it together."