The under secretary of energy oversees the department's energy and environment programs. The under secretary plays an instrumental role in the development of energy related research and development necessary to meet the United States' growing energy need and work to advance the nations energy and electricity security.
The under secretary of energy is appointed by the president with the advice and consent of the Senate. The current acting under secretary is Alex Fitzsimmons, who was appointed when Preston Wells Griffith III, who was sworn in on July 10, 2025, was removed on October 20, 2025. Kyle Haustveit was nominated to be the new under secretary in February 2026.