"I'm here today to again apologize for the personal mistakes I have made and the embarrassment I have caused," he said reading from a brief statement in Brooklyn.
"I make this apology to my neighbors and my constituents, but I make it particularly to my wife, Huma."
Weiner's wife was absent as he announced his decision, as she was 10 days ago when he admitted having sent inappropriate messages and photos to several women online.
Weiner said he had hoped to remain in Congress but conceded his predicament had made that impossible. Instead, he said he would resign "so my colleagues can get back to work, my neighbors can choose a new representative and, most importantly, that my wife and I can continue to heal from the damage I have caused."