 On 9 August 2008, Koh was conferred with the Order of Nila Utama (First Class) by the Singaporean government for his outstanding contributions in the Singapore legislative team representing Singapore in the Pedra Branca dispute case with the Malaysian government.In 2014, Koh received the Great Negotiator Award from Program on Negotiation at Harvard Law School for his multiple contributions to diplomacy, most notably his work as chief negotiator for the United States–Singapore Free Trade Agreement, his work around developing the Association of Southeast Asian Nations, his important efforts in resolving territorial and humanitarian disputes in the Baltics and Asia, and his success in leading both the Third UN Conference on the Law of the Sea and the UN Conference on Environment and Development (also known as the Rio Earth Summit).Koh is on the panel of mediators for Singapore International Mediation Centre.