Arngerður has always been interested in all kinds of music and has taken on various jobs over the years, for example as a producer and a technician at the Icelandic National Radio, a choir singer, a piano teacher, project manager, accompanist and choir conductor. Her main profession for the last years has been organist and musical director at one of the churches of Reykjavík, Laugarneskirkja but in year 2019 she decided to focus more on composition among with other creative projects. Today she is a freelance performer, composer, organist and choir conductor.
Arngerður has been active as a composer since 2017 and has mainly been writing for choir, string quartet and chamber orchestra. She has as well composed some music for the ensemble Umbra, which she is a member of. Umbra is a group of four women who all are professional musicians and focus on medieval music and the icelandic folkheritage. They have published four critically acclaimed albums and received the Icelandic Music Awards 2018 for the best album in the folkmusic genre.