He now faces a sentence of up to 10 years in prison
Former New York congressman Anthony Weiner has pleaded guilty to transferring obscene material to a minor.
52-year-old Weiner pled guilty to one count, which carries a maximum sentence of 10 years in prison.
According to information filed and statements made in Manhattan federal court, between in or about January and March 2016, Weiner used online messaging and video chat applications to communicate with a girl he knew to be 15-years-old.
In the course of those communications, Weiner transferred obscene material to her - including directions to engage in sexual conduct and sexually explicit images.
He surrendered to the FBI in New York Friday morning, and pled guilty before United States District Judge Loretta A Preska.
He was released on bail pending sentencing, which has been scheduled for September 8th.
Acting Manhattan US Attorney Joon H Kim said: "Today, former Congressman Anthony Weiner admitted and pled guilty to sending sexually explicit images and directions to engage in sexual conduct to a girl he knew to be 15 years old.
"Weiner's conduct was not only reprehensible, but a federal crime, one for which he is now convicted and will be sentenced. We thank the FBI and the NYPD for their work in this investigation."
FBI Assistant Director in Charge William F Sweeney Jr added: "We work every day in the FBI and law enforcement to stop adults from preying on vulnerable children.
"Our partnership with the NYPD cannot be stressed enough in this case, and we would like to thank the Special Victims Unit for all the work and effort they put into this investigation."
Weiner, a Democrat, resigned from the House of Representatives in 2011 after mistakenly tweeting an explicit image of himself that was intended as a direct message.
His wife, former Hillary Clinton aide Huma Abedin, announced in August 2016 she was splitting from her husband.