Tjøgersen, born in 1982, began her career as a clarinetist but now focuses on composition. She grew up in Southern Norway playing in a brass band and studied clarinet at the Norwegian Academy of Music without initially considering composition. She felt freer when she started composing, as she described: 'It felt freer.' Tjøgersen was asked by German composer Carola Bauckholt if she composed, and she replied 'yes, a little.' She was later invited to study composition at the Anton Bruckner University in Linz, Austria, where Bauckholt was a professor.
Tjøgersen values collaboration with orchestra members and brings a notebook to concerts to capture ideas. She describes composing as 'always having an exam, always delivering.' She has won several awards, including the Arne Nordheim Composer Prize in 2020 and the Ernst von Siemens Composer Prize last year. She was nominated for Spellemann for International Success of the Year in 2022 and 2023, and won Spellemann as composer and in the contemporary class for her debut album 'Between Trees' in 2024, as well as another Spellemann in March for 'Night Lives'.