The Hamnet actor, 30, put on a loved-up display with his girlfriend Gracie Abrams as they hit the red carpet at the Dolby Theatre for the 98th Oscars on Sunday.
Mescal has been drafted in to play McCartney in a four film anthology about The Beatles and their rise from Liverpool's Cavern Club to become the most influential band in the world.
During filming in Liverpool on Wednesday, stars Paul Mescal and Harris Dickinson were seen tucking into a portion of chips during a break from filming.
The 30-year-old, who is nominated for Best Supporting Actor for his role as William Shakespeare, cut a dapper figure in a a black suit which he layered over a silk shirt and necktie.
The Irish star is currently working with director Sam Mendes on a four film anthology about The Beatles and their rise from obscurity to become the most influential band in the world.
This year's Bafta Film Awards had it all... A-listers, a touch of royalty, Paddington Bear - and the sun even came out, for what felt like the first time all year.