He joined the Mandarin Oriental Hotel HK as Assistant Executive Pastry chef where he worked with chef Yves Matthey. In 2006 he went to France where Koo had the chance to learn from the reputed French chef and the owner of 13 Michelin-starred restaurants, Pierre Gagnaire. Koo participated in the 2007 World Chocolate Master competition in China where he received the “Best Taste Award”. In 2009 and 2010, Koo represented Hong Kong as their National Culinary team’s Pastry Chef.