Robert De Niro Reacts to Seeing Himself De-Aged in 'The Irishman' (Exclusive)

The actor also opened up about how it feels to see the project come to fruition after nearly 15 years of development.

For The IrishmanRobert De Niro's latest mobster drama with his longtime collaborator, Martin Scorsese, the actor had to play a character whose life plays out on screen through all the different stages of his storied and brutal career.

While the Hollywood of yesteryear would have required hiring a younger actor and applying prosthetic makeup for his older scenes -- or, having someone else play De Niro during earlier stages in his life -- newly developed digital cinema wizardry has made it possible to de-age the 76-year-old star with computer graphics.

It might seem like a real head-trip to see a much younger version of yourself on screen in a project you just filmed, but De Niro says he was just happy that the technology was able to serve it's story-telling function.

The actor walked the red carpet outside the theatrical premiere of the Netflix original drama at the TCL Chinese Theater in Hollywood on Thursday, and he opened up to ET's Lauren Zima about the project, which has been in development for quite some time.

When asked what it was like when he first saw the de-aged footage of himself, De Niro said with a shrug and a nod, "It was OK. I just wanted it to work as best as it can."

"And they did a very good job, I felt," he added of the computer graphics and editing team responsible for the impressive feat. "They tried to make it the best to date that it could be."

De Niro's measured yet supportive reaction could be due to the relative infancy of the technology responsible for the process, which has already been used by several other films -- most notably, Marvel Studios, who used the technology to de-age Kurt Russell for select scenes in Guardians of the Galaxy Vol. 2, and Samuel L. Jackson for the entirely of his starring performance in Captain Marvel.

In The Irishman, De Niro plays Frank Sheeran, an infamous real-life mob hit man, who recounts his life story from his service in World War II through the notorious disappearance of teamster and labor union organizer Jimmy Hoffa.

It's a project that has been percolating since 2004, when De Niro first became interested in the story, as told in the true crime book I Heard You Paint Houses. Scorsese began development on the film in 2007. However, the production faced numerous hurdles during it's decade and a half stuck in development hell, before pre-production began in earnest in 2016 and filming kicked off in September 2017.

So, for De Niro and Scorsese, this film has been a long time coming, and the actor says he's  excited that the world is finally getting a chance to see it.

"We worked on it for a long time, so finally we were able to do it and complete it and get it out," De Niro shared. "So we're very happy that we were able to do it."

The Irishman hits select theaters on Nov. 1, and premieres on Netflix Nov. 27.