Söderberg is known for his interpretations of baroque music, Mozart and Wagner, in roles such as Idomeneo, don Ottavio, Lurcanio, Oronte and Loge. Earlier he has also been the lead singer in operas such as Greve Almaviva, Lenskij, Rodolfo and don José. In 2005 he had the lead role in a modern interpretation of the opera Temistocle by Johann Christian Bach. During the summer of the same year Söderberg made his writing debut at the Drottningholm Palace Theatre as Oronte in the opera Alcina along with Anne Sofie von Otter and Christine Schäffer. In 2007 he had the lead role in L'Orfeo by Claudio Monteverdi and in 2012 the lead role in Orlando by Joseph Haydn. During 2011 he was part of Värmlandsoperan's interpretation of Wagner's Ring in the role as Loge. At Malmö Opera Rickard Söderberg has played the role of Idomeneo along with Malena Ernman. He has also had roles in Rucklarens väg, Karmelitsystrarna, Madama Butterfly, Hoffmans äventyr, Trollflöjten, Don Giovanni, Elias and Let's make an Opera by Benjamin Britten. In 2013 he participated in the TV4 show Körslaget, being the leader of the choir from Halmstad. He finished third in the show. Söderberg in a duet with Elize Ryd has participated in Melodifestivalen 2015 in hopes of representing Sweden in the Eurovision Song Contest 2015 in Vienna, Austria, but their song did not qualify. Söderberg participated in Let's Dance 2016 which was broadcast on TV4.
