He has been a regular member of the Denmark national football team since his debut in 2001, and has played 92 matches, scoring six goals for his country. He represented Denmark at the 2002 FIFA World Cup, 2010 FIFA World Cup and 2004 European Championship international tournaments. Poulsen was named 2001 Danish "under-21 Player of the Year", and won the 2005 and 2006 Danish "Player of the Year" awards; the first to win two years in a row.