Hartelius has previously been ambassador to Poland 2008–2010, Estonia 2003–2008, stationed in Saint Petersburg, Moscow, Berlin and London, vice president and director for the programme for European security at the EastWest Institute in New York, and a Permanent Representative of Sweden to the European Union.
In 2007, Hartelius participated as a celebrity contestant on the second season of Tantsud tähtedega, an Estonian version of Dancing with the Stars. His professional dancing partner was Kristina Tennokese.
- "Ambassadör Dag Hartelius utses till ny generaldirektör för Försvarets Radioanstalt". The Swedish Government Offices. Retrieved 12 March 2014.