In 2003, United Nations High Commissioner for Human Rights Sérgio Vieira de Mello invited Schwartz to join the Office of the United Nations High Commissioner for Human Rights. After Vieiera de Mello's assassination in the Canal Hotel bombing, Schwartz served as Chief of Office in the Geneva Office of the United Nations High Commissioner for Human Rights. He served there until 2004. In 2005, Secretary-General of the United Nations Kofi Annan appointed Schwartz as UN Deputy Special Envoy for Tsunami Recovery in the wake of the 2004 Indian Ocean earthquake and tsunami. In this capacity, Schwartz served under Bill Clinton, who was the Secretary-General's Special Envoy. He served as Deputy Special Envoy until 2007.