Growing up on a small farm outside Cape Town, Johnsen signed up for piano lessons after watching a 20th-anniversary rerelease of Amadeus. Since then, notable career highlights include scoring the HollyShorts selected drama Shouting at the Sea, winning ‘Best Music’ at the Top Indie Film Awards for Danny Cotton's Futurity Infinite, and ‘Best Score’ at the Royal Wolf Film Awards for Cotton’s follow-up, Collide. Additionally, Johnsen produced Mo Phoenix’s “Pearl” for Sky’s 2024 Fallen series and orchestrated Sebb Masters’ single “Something’s in the Water” for Blend Films’ Contact Hours.
As of 2025, Johnsen has assisted Golden-Globe-Winner Patrick Doyle, Dutch-German Composer Jan Willem de With, and Matthew Slater’s music preparation team for Dreamworks’ The Wild Robot and Hulu’s Alien: Earth.
Outside of film, his collaborations include Tête à Tête Opera (Three Penelopes), the English National Ballet School (ENBS Young Choreographers 2023), the Frozen Light Theatre Group (2065), and Emmy-award-winner Hugh Wooldridge (The Last Broadcast).
Johnsen studied music at Durham University before pursuing composition under Dimitri Scarlato and Haris Kittos at the Royal College of Music.
Films
Strings Attached by Danny Cotton (2025)
The Rounds by Asa Gartland (2025)
Additional music for Rockaruma by Alexandra Brandl (2025)
Michael by Albert Graver (2024) - Feature Film
Shouting at the Sea by Toffee Hammer Productions (2024)
HollyShorts Official Selection (2024)
Hold… Please! by Asa Gartland (2024)
Best Score nominee at Watersprite Film Festival
Best Student Film at the Big Fridge Film Festival 2025
Collide by Danny Cotton (2024)
Orchestrator for Contact Hours by Harry Richards (2024)
Oak by Roshni Bohra (2024)
Future Infinite by Danny Cotton (2023)
Best Score winner at Bharatha Desam International Film Festival
Decay of Spring by Rebecca Heath (2023)
Dalton’s Choice by Weiheng Kong (2023)
Bitten by Harold Rapport (2023)
Finders Keepers by Asa Gartland (2023)
Lost by Max Marshall (2023)
The Hand Print by Lanna Winter (2023)
The Right Film by Gregory Randolph (2023)
Blush by Shengyuan Tong (2022)
A Sense of Mothers by Lissete Picó (2022)
Hollow House by Bailey Fallgate (2022)
Such A Sweet Guy Was He! by Zhanbo Yu (2022)
Bigger Kid (short) by Harrison Sherlock (2022)
Best Film Runner Up at 2022 BFI/LSBU Awards
Firewatch (short) by Wilfred Wang (2022)
Goodnight Vienna (short) by Guy Taylor (2021)
Best Score nominee at 2021 Big Fridge Film Festival
Ascension Chronicles by Danny Cotton (2021) - Feature Film
Best Score winner at 2021 Royal Wolf Film Festival
Quest for Steel by Simon Roptell (2020) - Feature Film
Rhythm Adjustment by Adam Sturman (2020)
Parsley’s Protest (short) by Florence Lane (2020)
Baroque Animals by Maxime Tiberghein (2020)
Life Without Electric by Emily Ng (2020)
Documentary
Realm of Dreams by Holden Boyles (2023)
The Joy of Why (podcast) by Quanta Magazine (2022)
Watering the Withering Fields by Barry Savory & Hugh Wooldridge (2021)
Theatre
The Last Broadcast (Play) by Carey Crim – Additional music (2021)
Premiered at Riverside Studios, Hammersmith. Directed by Hugh Wooldridge.
2065 (Musical) - Arranger/Orchestrator (2021)
Composer’s assistant to Sam Halmarak. Musical commissioned by Frozen Light Theatre Group.
Concert Music
Streeting Beauty (chamber ensemble & synthesizer)
Premiered at the Wallace Collection in collaboration with the English National Ballet School (2023)
Dancing in a Black Lagoon (piano)
Premiered at the Royal College of Music’s Composer Showcase in collaboration with Roberto Boschelli (2023)
Three Penelopes (short opera)
Premiered at the Britten Theatre in collaboration with Tête à Tête Opera and the Royal College of Music (2022)