Ken turned professional in 1999 after college with a handicap of +2.5. In 2000 he played mainly on the Challenge Tour and claimed his first professional win at the Tessali Open del Sud in Italy with a record score. He won a second time on the Challenge Tour in 2001 by capturing the Challenge Total Fina Elf in France with another tournament record. He gained a full European tour card in 2002 and managed to secure his playing rights for 2003 mainly thanks to a third place finish in the French open and 10th place in Spanish open.

In 2003 he had his major break through win on the European Tour at the Canarias Open de Espana in a two - hole playoff, this gave him a two - year exemption. In 2005 he supported the Northern Rock Masters by playing in the tournament held at Matfen Hall, he won this in a four - hole play off against his coach John Harrison. That year he won for the second time on the European Tour, the Smurfit European Open, one of the most prestigious events in Europe, which carries a five year exemption and guarantees his participation on tour until 2011. He finished runner up at the Dunhill Championship at St Andrews later that year and followed up with a top ten at the end of year Volvo Masters which gave him his most successful year to date, finishing 11th on the order of merit.

This past year he was a member of the winning Europe team at the inaugural Royal Trophy in Thailand. The highlight of the year and the performance that brought Ken more into the public eye was the 2006 U.S. Open at Winged Foot, New York, where he led the tournament for most of the week. He played in the final group with world number two Phil Mickelson on Sunday and ended up finishing in sixth place, this qualifies Ken to play in the coming US Masters and a return to the US Open. He was hit by injury at the Open at Royal Liverpool and was forced to withdraw during the second round and missed most of the rest of the season as a result, he narrowly missed out on a return to the K Club as a member of the European Ryder Cup team, this still remains an ambition of his.