With his men's doubles partner Lars Paaske he won the 2003 IBF World Championships defeating Indonesian pair Candra Wijaya and Sigit Budiarto in the gold medal match and the All England Super Series 2010 defeating compatriots Mathias Boe and Carsten Mogensen.

In the quarterfinals, Rasmussen and Olsen beat Kim Dong-moon and Ra Kyung-min of Korea 17–14, 15–8 to advance to the semifinals.

In the bronze medal match, they were defeated by fellow Danish pair Jens Eriksen and Mette Schjoldager 15–5, 15–5 to finish fourth place.

He won the gold medal at the 2008 European Badminton Championships in men's doubles with Lars Paaske.

[1] With the retirement of Lars Paaske after the 2010 BWF World Championships in Paris, He is now pairing with another Danish player, Mads Conrad-Petersen.