In Sweden, Källvik is known primarily as a singer, and he tours the country every summer singing popular Swedish folksongs. He has also appeared in various musicals staged at Swedish theaters. Källvik's voice credits include Lucky Luke (as Joe Dalton), Disney's Tale Spin, Alice in Wonderland (as the Dodo and Caterpillar), Ducktales: The Movie, Treasure of the Lost Lamp (as Launchpad McQuack and Merlock), Flubber (dubbing Ted Levine), Astérix et la surprise de César, and many others.