Wilhelmsson won 79 caps for the Sweden national team between 2001 and 2012, and represented his country at the 2006 FIFA World Cup and at Euro 2004, 2008, and 2012.

Anderlecht in Belgium, being an undisputed starter during his spell and scoring nine top division goals combined in the capital side's 2004 and 2006 league conquests.

He made his Serie A debut on 14 January against FC Messina,[2] Roma did not take advantage of its option to buy and Wilhelmsson returned to Nantes after the season and immediately starting seeking a new club following the Canaries' relegation from Ligue 1.

He helped the club win the league title in his second year, scoring nine goals and making ten assists in 20 appearances; for his contributions he received the Player of the Season award, going on to win four additional major titles during his tenure, including two consecutive Saudi Crown Prince Cup where he scored in both finals.

[17] Wilhelmsson scored his first brace for Sweden in a Euro 2012 qualifier against San Marino on 6 September 2011 (5–0 away win), for his seventh and eighth international goals.

[18] He was also selected for the finals in Poland and Ukraine by manager Erik Hamren, collecting three bench appearances in an eventual group stage exit.