Kjellbin was a member of the Swedish national under-18 ice hockey team at the 2011 IIHF World Women's U18 Championship, getting two assists in five games. She represented Sweden again at the 2012 IIHF World Women's U18 Championship, getting four points in six games as Sweden won bronze and scoring her first international hat-trick in their group stage match against Russia after being selected to take a penalty shot. She won a gold medal with Sweden at the 2012 Winter Youth Olympics.