The South Indian actor, real name Venkatesh Prabhu Kasthuri Raja, has traded his star billing in Tamil cinema for a supporting role in the action blockbuster, out Friday in cinemas and on Netflix on July 22.
In his debut Hollywood outing, Dhanush joins a killer cast, led by Ryan Gosling, Chris Evans and Alfre Woodard, in a thrilling spy tale based on the series of novels by Mark Greaney.
Directed by Anthony and Joe Russo, the brothers behind Avengers: Endgame, the big-budget film aims to be a launch pad for a possible franchise.
Dhanush says working on the film gave him "an understanding on how Hollywood works."
"I have done about 50 films in 22 years of work in the Indian film industry and you don't often get a chance to feel like a newcomer because that first time it all happens in a blur and you don't know what's happening," he says, during a press conference held for the film.
"But this time, I had an opportunity to look at myself like a newcomer and it was amazing because I grew up watching Hollywood films and to be in one is really nice."
The Gray Man follows the escapades of Court Gentry (Gosling), the titular character, a government mercenary operating under the code name Sierra Six.
After unexpectedly coming across dark state secrets, Gentry is on the run from assassins led by nemesis Lloyd Hansen (Evans).
One of those on the hunt is Dhanush’s character Avik San, with the role reportedly written for him by the Russo brothers after becoming enamoured by his work in Bollywood films. Dhanush is one of the few actors who've had success in the South Indian as well as the more famous Hindi film industries.
"Avik San is supposed to be very calm, mysterious and composed but with this kind of moments and energy," Dhanush says. "He is a character that keeps you thinking all the time."
While no stranger to large-scale action scenes, Dhanush says it took some effort to adjust to the Russo brothers' particularly kinetic form of filmmaking.
"I had one-and-a-half months of training and a week before I started filming, I sprained my neck and I was like 'damn, what am I going to do now?' The physio had a week's time to get me ready," he recalls.
"Somehow they found a way to make me fit for the stunt sequence and it was just an amazing experience."
From 'Bridgerton' to the CIA
The British actor is calculating and quietly malevolent as CIA director Denny Carmichael, as he considers whether one of his best assets, Gentry, has become surplus to requirements.
"I try to cover each script like a duckling that has never seen a script before in my life and I start fresh. I wanted to make sure this guy has a background and a reason to be the way he is, because the immediate reaction to Carmichael is you look at him and go 'who does this?" Page says.
"So I wanted to give him a bit of depth and something interesting in his background... something aspirational to explain why he is pushing himself so hard."
The ambition and scope is also being mirrored behind the camera.
A $200 million production, The Gray Man is the most expensive film Netflix has made and Anthony confirms it will feature some spectacular action sequences shot in Prague, capital of the Czech Republic.
"We needed a large section of the city in order to pull that off because it starts in a major city square and features a chase down the city," he says.
"Just to show you hard it was, there is a tram The Gray Man gets on and it careens through Prague and to shoot that sequence, we used actual trams and a bus that we designed to look exactly like a tram, but ran on wheels. This is because sometimes we needed the tram to go faster than it could actually go or take it down streets that have no tracks.”
More to come from 'The Gray Man'
Joe praised the cast's mix of young and seasoned talent for contributing to the evolution of the script.
"We wanted them to have emotional ownership over the characters because everyone here is a great storyteller as well as an incredible actor," he says.
"They have such an amazing wealth of experience and we encourage all of our collaborators to bring that to the table.
With each actor intriguing enough to have their own movie, Anthony is hopeful of releasing sequels to The Gray Man.
"Look, part of our motivation to assemble a cast like this, who can embody so many interesting characters, was the hope of creating a universe you want to follow," he says.
"So yes, hopefully there will be more stories to tell in The Gray Man world."
The Gray Man is out in cinemas on Friday and streams on Netflix from July 22