The ban, which is sparking a nationwide debate about freedom of speech, is really Twitter's attempt to show it is cracking down on targeted abuse.
Yiannopoulos has used the social media site for years to not only voice his controversial opinions but to direct his followers toward his opponents.
He has actually been temporarily suspended from Twitter a number of times for violating its terms of service. He was even stripped of his verified status.
Last month, Yiannopoulos gave an anti-feminism speech at UCLA, which sparked protests from dozens of livid students.
But this week he apparently went too far.
According to Twitter, it was Yiannopoulos who led the harassment campaign against Jones, who stars in the new "Ghostbusters" movie.
Thousands of racist and abusive tweets were sent to the actress over the past few days - so many that she was forced to leave Twitter.
I leave Twitter tonight with tears and a very sad heart.All this cause I did a movie.You can hate the movie but the shit I got today...wrong— Leslie Jones (@Lesdoggg) July 19, 2016
This might have been the last straw for the social media site. However, the company says Yiannopoulos' permanent suspension isn't a matter of speech as much as a matter of behavior.
Twitter says he violated its rules regarding targeted abuse of users.
Yiannopoulos doesn't see it that way. He says the site is targeting him simply because of his conservative beliefs.
He issued the following statement, in part, on the Breitbart website:
"Like all acts of the totalitarian regressive left, this will blow up in their faces, netting me more adoring fans. We're winning the culture war and Twitter just shot themselves in the foot. This is the end for Twitter. Anyone who cares about free speech has been sent a clear message: you're not welcome on Twitter."
Here's is Twitter's response:
"People should be able to express diverse opinions and beliefs on Twitter. But no one deserves to be subjected to targeted abuse online, and our rules prohibit inciting or engaging in the targeted abuse or harassment of others."
News of the permanent suspension came just minutes before Yiannopoulos hosted his event "Gays for Trump" at the Republican National Convention.
Supporters of Yiannopoulos created #FreeMilo to protest his suspension, which at one point was accumulating 20 to 30 tweets per minute, Breitbart says.