Here is a look back at the events leading up to Monday's announcement.
A little-known U.S. representative in 2010, Weiner made national headlines with an angry floor speech in the House after a the defeat of a bill that would have provided funds for 9/11 responders.
But that attention turned negative less than a year later, when the first hints of scandal surfaced.
In May of 2011, a photo of a man in underwear appeared on Weiner's Twitter account but was later removed. After several days of swirling rumors, he claimed his account had been hacked.
The scrutiny only intensified as he appeared evasive and inconsistent in public. Just days after the hacking claim, he broke down in tears as he admitted to sending inappropriate online messages to several women.
Still, he refused to step down and said his marriage to Abedin would continue.
Just over a week later — amid a stream of embarrassing revelations and mounting pressure even from his own party — Weiner convened a news conference to announce his intention to leave Congress.
"I am announcing my resignation from Congress so my colleagues can get back to work, my neighbors can choose a new representative and, most important, so that my wife and I can continue to heal from the damage I have caused," he told reporters.
Weiner largely stayed under the radar until mounting a run for mayor of New York City in 2013.
After posting a surprisingly strong showing in early polling, he found himself again embroiled in controversy as more messages were made public.
"These things that I did were wrong and hurtful to my wife," Weiner said at a press conference, with Abedin appearing by his side. "This behavior is behind me. I have apologized to my wife, Huma, and I am grateful that she has worked through these issues with me and that I have her forgiveness."
He said the messages came from past mistakes, but it later was revealed that his online relationships with women continued after he resigned from Congress.
Despite protests, including ones from Democratic backers, he soldiered on in his mayoral bid, finishing a distant fifth in the Democratic primary.
In 2014, Weiner apologized after marking as a favorite a tweet that called the dating app Tinder the "ultimate sext machine."
Earlier this month, The New York Post reported that he exchanged suggestive messages with a person he thought was a female college student but was actually a man baiting Weiner.
Through it all, his marriage to Abedin continued.
The revelations on Monday appeared to be the final straw for Abedin, who announced her intention to end their relationship and asked the public for privacy.