Delaney made his stage debut in Beth Steel's "messy but compelling" drama
Labyrinth that was produced at the
Hampstead Theatre in 2016, earning a place on the
Evening Standard's
Theatre Emerging Talent Award list. In 2018, Delaney played Michael Carney in
Jez Butterworth's hit
play The Ferryman, directed by
Sam Mendes and staged in the
Gielgud Theatre. Subsequently, he was invited to work in the
Stateside production of the play that was staged on
Broadway's
Bernard B. Jacobs Theatre. The same year, he was cast as Kenny Stowton, an ex-hacker recruited by
MI6, in
BBC's hit
black comedy-
spy thriller TV series
Killing Eve. His "quirky, fan-favorite" character started off as a temporary one but turned into a "re-occurring and quite integral" part of the hit show. Head writer Suzanne Heathcote rated his work in the series as "brilliant." In 2022, Delaney started working in the Charlie Stratton-directed film
Seacole, along with
Sam Worthington,
Gugu Mbatha-Raw, and
Rupert Graves. ==Personal life==