Born in Farsø, Krøldrup started his footballing career at Danish lower league clubs Farsø/Ullits IK and Aalborg Chang.
He then went on to play for Copenhagen-based B.93 in the second-tier Danish 1st Division before transferring to Udinese in the Italian top-flight Serie A championship in 2001.
[3] In June 2005, Krøldrup moved from Udinese to English club Everton on a four-year deal for a transfer fee of £5million.
[9] Krøldrup transferred back to Italy on 19 January 2006, when he joined ACF Fiorentina, 31 days after his Everton debut.
[10] On 8 March 2013, Krøldrup signed a short-term contract with Serie A club Delfino Pescara 1936 for the rest of the 2012–13 season.