Paul was born on February 2, 1996, in County Kildare, Ireland to Paul and Dearbhla Mescal.
He was raised alongside his sister Nell and a brother Donnacha.
His father Paul was the state police force of the Irish Republic while his mother is a schoolteacher.
From an early age, Paul was interested in sports. He was a good footballer and was an under 21 footballer for Kildare.
Regarding his education, Mescal graduated with a Bachelor of Arts in Acting from The Lir Academy at Trinity College Dublin in 2017.
He graduated with a Bachelor of Arts in Acting from The Lir Academy at Trinity College, Dublin in 2017.
Upon graduating from drama school, Mescal was offered roles in two theatre productions, Angela's Ashes and The Great Gatsby; he took on the latter and starred as the titular Jay Gatsby at the Gate Theatre in Dublin.
He also played the Prince in a contemporary retelling of Hans Christian Andersen's The Red Shoes at the same theatre that year.
In December, he starred in Phoebe Bridgers' music video for the song "Savior Complex", which was directed by Phoebe Waller-Bridge.