His works have seen performances throughout the Nordics, Russia, Australia, the U.S., Canada, England, Scotland, Greece, Estonia, Lithuania, Latvia, Poland, Germany, France, Holland and Japan.
His works have been featured at festivals such as the Bourges Festival for electro-acoustic music in France, the International Rostrum for Composers in Paris, the DUT-festival in Copenhagen, Nordic Music Days and the ULTIMA Oslo Contemporary Music Festival, performed by ensembles Cikada, Oslo Sinfonietta, BIT20 Ensemble and Ensemble Court Circuit.
In addition to his two operas, Sera and Ophelias: Death by Water Singing – both premiered at the ULTIMA Oslo Contemporary Music Festival and later performed in Poland and Germany – Hellstenius has also worked closely with playwrights Jon Fosse, Cecilie Løveid, Liv Heløe as well as choreographer Ingun Bjørnsgaard.
An example of this compositional practice is the project Ørets Teater I.IV, premiered at the 2011 Bergen International Festival, for which Hellstenius was composer in residence.
Following its premiere, the work was adapted and rewritten for a 2015 ULTIMA Oslo Contemporary Music Festival performance.