After completing the apprenticeship, Chef Kellerhoff joined the military service for one year. Upon returning to the culinary arts, he worked at a 16–point Gault Millau restaurant in Dortmund as Commis Chef, and later joined a 15–point Gault Millau restaurant in Muenster.

After spending some time working for one–Michelin–star and 17–point Gault Millau restaurant in Cologne, the opportunity arose for Sebastian Kellerhoff to move to the famous Five–Star Hotel Adlon in Berlin. During this time, the Hotel Adlon was voted the best hotel in Europe and its restaurant was awarded one Michelin Star.

After two and a half years as a Sous Chef in Berlin, Chef Kellerhoff moved to Dubai to join the team at Hyatt Regency Dubai. He then furthered his culinary expertise in the position of Executive Sous Chef at the Grand Hyatt Dubai for two years.

Most recently, Chef Kellerhoff joined the Hyatt team to assist in the openings of Hyatt Regency Kiev hotel in Ukraine and Hyatt Regency Ekatirenburg hotel in Russia. Further, Chef Kellerhoff was offered the position of Executive Chef at the Hyatt Regency Kiev, and was voted one of the best 25 chefs in Ukraine. He has also been featured on Ukrainian television.