Born in Makkinga, Friesland, Kromkamp made his professional debut for Go Ahead Eagles in Eerste Divisie, his first appearance in the competition being on 12 September 1998 in a 3–0 home win against FC Top Oss.

[4][5] Kromkamp made his debut for the Reds on 7 January 2006, in a 5–3 win over Luton Town in the third round of the FA Cup.

During his stint at Anfield, however, he was unable to dislodge Irish international Steve Finnan from the starting lineup, but did make a number of appearances from the bench, most notably in the domestic cup final; he was described as being a fair crosser of the ball with a lack of pace, who had difficulty in stopping opposition wingers getting crosses in.

On 31 August 2006, he was sold to PSV Eindhoven,[7] taking over the number 2 jersey from André Ooijer who left for Blackburn Rovers.

[8] On 23 June 2013, aged 33, Kromkamp announced his retirement from professional football due to chronic knee problems.