The Normal People breakout star is to star along side The Crown star O'Connor in a filmed dubbed a "universal love story".
The film is "follows two young men, Lionel (Mescal) and David (O'Connor), who, during the WWI period, set out to record the lives, voices and music of their countrymen. In this snatched, short-lived moment in their young lives, and while discovering the epic sweep of the USA, both men are deeply changed".
It is adapted from Ben Shattuck's short story of the same name and is directed by Oliver Hermanus. It is due to start production next Summer and will be shown in the UK, Italy and the US.
Speaking on the film, Oliver Hermanus also praised the writing of Shattuck.
"I instantly fell in love with Ben Shattuck's flawlessly beautiful short story and knew I had to be involved in its journey to the screen", he said.
Hermanus also added, "Paul and Josh are two of the most promising actors of their generation who will share with us deeply soulful performances".
"This is an unexpected love story that needs to be told - it is a journey through the life of America, across the 20th century and the traditions of American folk music, all seen through the bond between two men immersed in the history of sound".
"This undeniably powerful story will certainly resonate with audiences the world over".
Paul Mescal is due to hit the screens in December, when he features alongside Olivia Coleman in The Lost Daughter. This will hit the cinemas on December 17 and Netflix on December 30.
Check out the trailer below.
Olivia Coleman will also star alongside Josh O'Connor in the film Mothering Sunday which will arrive on November 12.
