After portraying Anneli in the early 2000s television series Skolen, Kittelsen starred as Liv Heyerdahl and Tikken in the respective films Kon-Tiki and Max Manus.
After finishing her training at the Norwegian National Academy of Theatre, she performed at both Den Nationale Scene (in Bergen, Norway) and the Norwegian National Theatre (in Oslo).
She starred in the 2010 Norwegian film Happy, Happy. The movie won the Sundance Film Festival's World Cinema Grand Jury Prize and subsequently became Norway's entry for the Academy Award for Foreign Language Films.
She was born and raised in the southern Norwegian city of Kristiansand. She married Lars Winnerback in 2016. In 2019, their daughter was born.
She and Chernobyl Diaries actress Ingrid Berdal were born in the same year and both attained considerable success in the Norwegian cinema.