Jones was suspended from Twitter for one week last month after he posted a video in which he said, "Now is time to act on the enemy before they do a false flag." But Twitter did not ban him from its platform then, even after YouTube, Apple and Facebook each kicked him off.
In a series of tweets from its @TwitterSafety account, Twitter said, "Today, we permanently suspended @realalexjones and @infowars from Twitter and Periscope. We took this action based on new reports of Tweets and videos posted yesterday that violate our abusive behavior policy, in addition to the accounts' previous violations."
Twitter also said that it "will take action" if in the future it discovers other accounts being used to get around the ban of Jones and InfoWars.
The company made its decision a day after Jones accosted a CNN reporter, Oliver Darcy, on Capitol Hill, and livestreamed the encounter through Periscope, which Twitter owns.
Jones and InfoWars are notorious for spreading conspiracy theories and other demonstrably false information, including the idea that the Sandy Hook massacre was a hoax, and that the victims of it were child actors. Some of the parents of the victims have sued Jones for mental and emotional distress.
Jones had traveled to Washington D.C. Wednesday for congressional hearings at which Twitter CEO Jack Dorsey and Facebook COO Sheryl Sandberg testified.
Before accosting Darcy, Jones confronted Senator Marco Rubio in a hallway outside the room where Dorsey and Sandberg were appearing for a Senate Intelligence Committee hearing.
Jones repeatedly interrupted Rubio as the senator answered questions from reporters. After Jones tapped Rubio on the shoulder, the senator warned, "Hey, don't touch me again, man."
Later, he found Darcy outside a room where Dorsey was to appear before the House Energy and Commerce Committee.
Darcy's reporting had previously raised questions about tech companies' rules and statements about their battles against misinformation, and whether those were consistent with their allowing Jones and InfoWars to use their platforms. For example, after Dorsey himself tweeted that Twitter was not banning Jones like its counterparts had because "he hasn't violated our rules," an investigation by Darcy led to Twitter admitting that in fact at least seven tweets had broken its rules.
Jones shouted at Darcy for more than ten minutes, accusing him of being in favor of censorship and insulting his appearance, comparing him to "a rat" and told Darcy he was "evil-looking." Jones was live on Twitter's Periscope service the whole time.