Christiansen has played 338 games for the Danish national team,[3] and scored 1503 goals.[4] He is currently the player with most games and most goals for the Danish national team.
He played for the German club SG Flensburg-Handewitt, and was part of the team when the club won the German championship in 2004, and won the EHF Cup in 1997. In his 14 years with SG Flensburg-Handewitt he scored 3996 times, 1623 of these was scored from the 7 meter penalty spot.
Lars Christiansen's cousin Jan Paulsen has played together with Lars Christiansen for the Danish national handball team - as playmaker.
He has been married to former handballer, Christina Roslyng, who played at the Danish national handball team. Together, they have two sons, Frederik and August. They split up in 2009, however, as of 2012, they are back together.