Her practice began in narrative theatre and experimental opera After a period working for London's Bush Theatre, she first worked for the National Theatre in 1998 when Trevor Nunn asked her to design the set for a revival of Harold Pinter's Betrayal. She has since worked on sculptural designs for the theatre. "Each of her designs is an attack on the notion that a set is merely scenery" wrote Andrew O'Hagan in The New Yorker in 2016. Devlin "is in demand because she can enter the psychic ether of each production and make it glow with significance."
In September 2018 it was announced that Devlin will design the UK Pavilion at the 2020 World Expo in Dubai. Known as the Poem Pavilion, it will feature an illuminated 'message to space' to which each of the Expo's anticipated 25 million visitors will be invited to contribute. Devlin is the first woman to be commissioned by the UK since world expositions began in 1851.
Her luminous fluorescent red Fifth Lion sculpture roared A.I. generated collective poetry to crowds in Trafalgar Square during London Design Festival September 2018.The Singing Tree, her collective choral carol installation at the Victoria and Albert Museum, fused machine-learning with sound and light and was viewed by over ten thousand visitors during Christmas 2017; her Mirrormaze generated queues around the block in Peckham in 2016. Further explorations of labyrinthine and map based geometries led to the 7000 square foot hotel room odyssey Room2022 at Art Basel Miami 2017 and the projection-mapped ovoid model city MASK at Somerset House 2018.
The designer collaborated with the theoretical physicist Carlo Rovelli on an interpretation of The Order of Time read by Benedict Cumberbatch at the legendary rooftop art space, BOLD Tendencies in Peckham in September 2018.