Jonnie played Nat in The Unreturning.

He is an actor, director and movement director. As an actor, he has appeared in This Will All Be Gone (Frantic Assembly, Asian tour), No Way Back (Frantic Assembly/Made in Corby), Full Stop (Light The Fuse/Lyric Hammersmith/Greenwich and Docklands International Festival), Canticles (Brighton Festival/Aldeburgh Music/Frantic Assembly), The Marriage of Figaro (Opera Holland Park), Night Film (Stand + Stare), Mortal: A Drama (Wellcome Collection), The Fear (Frantic Assembly's Ignition) and In His Image (Hampstead Theatre)

Jonnie is also associate director of ThickSkin, appearing as an actor in their productions Boy Magnet and These Imagined Stories and directing Boy Magnet and White Noise.

Other directing credits include the first stage adaptation of Nigel Slater's Toast (The Lowry) and Found (The Albany). As movement director his credits include Great Apes (Arcola Theatre), Connections Festival 16/17 (National Theatre), Maggie & Pierre (Finborough Theatre), The Paper Birds’ Mobile (UK tour), Frozen Light’s Home (UK tour), CAUGHT (Pleasance Theatre) and Cracking, Hooked and Bat Boy (New Wimbledon Studio).