[9][10] Gaelic footballer Brian Lacey praised Mescal's skills as a defender,[11] while physical trainer Cian O'Neill said he is "mature beyond his years... very developed and very strong".

[16] The Irish Times Peter Crawley highlighted his work as a "butterfly of self-creation among an ensemble in constant motion and fluttering improvisation".

[18] Mescal appeared in the world premiere of the 2018 play Asking for It by Louise O'Neill at the Abbey Theatre in Dublin; Steve Cummins of The Times commended his distinctive performance.

[21] Mescal starred in his first television role in the drama miniseries Normal People, an adaptation of the 2018 novel of the same name by Sally Rooney.

[27][28] In their respective reviews for Variety and Slate, Caroline Framke called Mescal's navigation through the character's emotional collapse "breathtaking", while Willa Paskin noted his concurrent embodiment of "intelligence, insecurity and quiet confidence".

[33] He played a firefighter in the Channel 5 miniseries The Deceived and appeared in the music video for the song "Scarlet" by The Rolling Stones in August.

[34][35] Reviewing The Deceived, The Independent critic Ed Power highlighted Mescal's effortless "sleepy-eyed charm" and "flawless" Donegal accent.

[40][41] IndieWire critic Kate Erbland found Mescal's work in God's Creatures "powerful" and "quietly chilling".

[42] Reviewing Aftersun, Peter Travers of ABC News highlighted his "disarming charm and elemental power" in his portrayal of a "complex role".

[47] Mescal portrayed Stanley Kowalski in a revival of the play A Streetcar Named Desire by Tennessee Williams at the Almeida Theatre beginning in December 2022.

[48][49] The Times's Dominic Maxwell found him "tremendous" and opined that he "makes the latent violence of Stanley Kowalski into something easy, tangible, vibrant yet unactorly".

[56] He also starred opposite Saoirse Ronan in Foe, an adaptation of Iain Reid's science fiction novel of the same name;[57] the film was not well received by critics.

[61] Slant Magazine's Jake Cole wrote, "Mescal gives a performance that recalls Russell Crowe's no-nonsense Maximus from Gladiator, right down to speaking in some of the same cadences and inflections".

[77] He participated in a virtual stage reading of the play This Is Our Youth by Kenneth Lonergan as part of a series benefiting the Actors Fund of America charity in October 2020.