Born in Washington D.C., Hammer grew up in Latin America, living in Honduras, El Salvador, Colombia, Venezuela, and Brazil.

[5] Hammer served as Special Assistant to the President, Senior Director for Press and Communications, and Spokesman at the National Security Council at the White House from 2009 to 2011.

[8] On June 1, 2022, U.S Secretary of State Antony Blinken announced Mike Hammer as the new Special Envoy for the Horn of Africa under the Biden Administration, replacing David Satterfield.

[9] In late July the same year, Hammer visited Egypt and Ethiopia to build relations and discuss the Grand Ethiopian Renaissance Dam.

[15][16][17] In August 28, 2023, Hammer announced he would meet with Kenyan, Ethiopian, African Union and Intergovernmental Authority on Development (IGAD) officials to discuss ways to resolve a conflict in Sudan, which began earlier that year.