Lars Hjertner has attended Calle Flygare and Kulturama. Between 1990 and 2002, he was employed at Länsteatern in Skaraborg, where he performed in Maratondansen, Grease and the one-man performance Änglaknäpp. At the Oscars Theatre, Lars performed the title role in Cyrano, and in Himlaspelet, he performed the role of Mats. Since 2002, he has been involved with the Göteborg Opera, where his roles have included Lilleman in Stoppa Världen!, Lumière in Beauty and the Beast, Fred in Kiss me Kate and the title role in Chaplin. His most recent roles include The Director in Lasse-Majas detektivbyrå: The Opera Mystery and The Judge/Fyrstjärnan in Carmencita Rockefeller.