Fire Chief Dennis Rubin made the announcement in a mass email updating his contact information.
In the email, Rubin writes he will step down on Jan. 2 when "the new administration takes over." He adds that he plans to provide consultant services until he finds a position that is "a good fit."
Rubin became the fire chief in 2007.
D.C. Fire spokesman Pete Piringer says Rubin has not spoken with City Council Chairman Vincent Gray about the decision. Gray defeated Mayor Adrian Fenty in the mayoral primary.