Ragnheiður graduated with a masters degree in opera from the Royal Conservatoire of Scotland in 2014. Before moving to Scotland, Ragnheiður studied singing at the Reykjavik Academy of Vocal Arts and the Reykjavík College of Music with Alina Dubik and Lára S. Rafnsdóttir, where she was the winner of the Reykjavik College of Music soloist competition. Ragnheiður has participated in masterclasses with Rosalind Plowright, Janet Williams, Kristinn Sigmundsson, Dame Felicity Palmer and Malcolm Martineau among others.

Ragnheiður has sung the roles of Magda (La Rondine/Puccini), Vitellia (La clemenza di Tito/Mozart), Lady Billows (Albert Herring/Britten), Gertrud (Hänsel & Gretel/Humperdinck) as well as performed excerpts of roles such as Donna Anna (Don Giovanni/Mozart), Fiordiligi (Cosi fan tutte/Mozart), Alice Ford (Falstaff/Verdi) among others.

Ragnheidur has extensive choir experience, having sung with the Schleswig-Holstein Festival Choir, Choir of the Icelandic Opera and most recently the Lübeck Chorakademie on concert tours to Brazil, S-Korea, China and Germany.