Wolf's departure as head of the body in charge of security for President-elect Joe Biden's inauguration on January 20 came as worries rose over more violence during the inauguration.
“I am saddened to take this step, as it was my intention to serve the department until the end of this administration,” Wolf said.
The White House declined to comment.
Wolf resigned five days after President Trump's supporters stormed the US Capitol, hoping to prevent Biden from replacing him.
Education Secretary Betsy DeVos and Transportation Secretary Elaine Chao had earlier resigned n the aftermath of the Capitol siege.
The FBI has warned that armed Trump supporters could hold protests in all 50 states between the coming weekend and January 20, according to US media.
The White House issued a statement saying that Trump had "declared that an emergency exists in the District of Columbia and ordered Federal assistance to supplement the District's response efforts due to the emergency conditions resulting from the 59th Presidential Inauguration from January 11 to January 24, 2021."
It said the order gave the Department of Homeland Security the authority to act "to save lives and to protect property and public health and safety, and to lessen or avert the threat of a catastrophe in the District of Columbia."
Federal, city officials blame game over Capitol siege
Meanwhile, federal and city officials continued to point fingers over who was responsible for the Capitol assault last Wednesday, when the Congressional police force was overwhelmed by thousands of Trump supporters.
Two Capitol police officers were suspended as Washington continued to deal with the fallout of the riot ahead of Biden’s inauguration next week.
10 to 15 police officers were under investigation in relation to the Capitol siege, which led to the deaths of five people and interruption of the congressional certification of the US November election results.