The 33-year-old Briton had already lost a book deal and a speaking engagement over a video leaked on Twitter over the weekend in which he defends men having sex with children as young as 13.
Facing the media at a news conference in New York, Yiannopoulos yesterday announced he was stepping down as tech editor for the conservative site.
"Breitbart News has stood by me when others caved," he said, reading from a prepared statement.
Yiannopoulos is reviled by his critics as racist and misogynistic, but casts himself as a gay crusader against "political correctness."
More From This Section
He is often portrayed as a leader of the so-called alt-right -- a white nationalist extremist fringe that has found a home on Breitbart's pages -- although he has distanced himself from the movement.
Breitbart News issued a statement of its own, saying it had accepted Yiannopoulos' resignation, and adding that his "bold voice has sparked much-needed debate on important cultural topics."
"Pedophilia is not a sexual attraction to somebody 13 years old who is sexually mature. Pedophilia is attraction to children who have not reached puberty," he adds.
In a statement issued in response to the uproar, Yiannopoulos said he himself had been a victim of child abuse.
"My own experiences as a victim led me to believe I could say anything I wanted to on this subject, no matter how outrageous. But I understand that my usual blend of British sarcasm, provocation and gallows humor might have come across as flippancy, a lack of care for other victims or, worse, 'advocacy,'" he wrote.
It's not the first time the provocateur and staunch fan of President Donald Trump found himself mired in controversy: he was banned from Twitter for provoking online harassment of black actress Leslie Jones in July.
The University of California at Berkeley cancelled a planned speech by Yiannopoulos this month after protests against him turned violent. Trump reacted by threating to withhold federal funds from the university.