Julia Pierson, a secret service veteran who spent much of her career based in Florida, takes on responsibility for the safety of Obama and his family, the vice-president, other leading Washington figures and visiting international dignitaries. She is at present chief of staff at the secret service.
The reputation of the service was badly damaged after revelations in April last year about preparations for Obama's trip to Cartagena, Colombia.
Secret service employees, part of an advance team preparing for Obama's arrival, took prostitutes back to the hotel where they were staying. The incident raised questions about a macho culture alleged to be pervasive inside the service.
Pierson, 53, replaces Mark Sullivan, who retired last month after leading the agency for seven years. He faced heavy criticism on Capitol Hill over the Colombian scandal for which he apologised but insisted the president's safety had never been compromised.
By appointing a woman, the White House sends a message that a macho culture will not be tolerated.
The scandal tarnished the image of an agency that had previously been based on the notion that gents were prepared to put their lives on the line to protect the president and others under their watch
Obama, in his announcement, praised Pierson: "Over her 30 years of experience with the secret service, Julia has consistently exemplified the spirit and dedication the men and women of the service demonstrate every day."
He went on: "Julia has had an exemplary career, and I know these experiences will guide her as she takes on this new challenge to lead the impressive men and women of this important agency."
As well as its protection duties, the secret service is also involved in criminal investigations, mainly in the field of counterfeiting, and has 150 offices across the US.
Pierson, who is originally from Orlando and is a graduate of the University of Central Florida, began her career as a police officer in Orlando in 1980, joining the secret service in 1983 in Miami.
Obama said: "Julia is eminently qualified to lead the agency that not only safeguards Americans at major events and secures our financial system, but also protects our leaders and our first families, including my own."
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