[3][4] Andersen was a Danish Junior Champion in 1996 and reached the final of the 1999 Speedway Under-21 World Championship, where he finished fourth.

[4] During 2004 and 2005 he rode for Ipswich Witches and was an established member of the Danish national team as well as a regular rider in the Speedway Grand Prix.

[8] Shortly afterwards he signed for Coventry Bees and teamed up with Chris Harris to win the Elite League Pairs Championship.

Andersen rode for the Poole Pirates in 2009, and moved on to join the Belle Vue Aces for the 2010 season.

Andersen led Swindon Robins to Elite League glory in 2012, and on 28 January he eventually was able to ride for the Wiltshire side again in 2013 following a winter-long battle with parent club Peterborough.