Yiannopulos had also been scheduled to speak to Republicans at UCLA on Thursday, but that appearance had also been canceled, prior to the Berkeley protests.
A Facebook posting last week from the Bruin Republicans said the group's board decided they will no longer be able to host Yiannopulos.
Among the reasons: "We were unable to accommodate the long list of requirements that were set forth by Milo's team." The group also noted that safety was a concern given the violent protests at several of his events.
But an additional note in the post appears to contradict some of the reasons given in the initial letter, stating: "To clarify: we are not canceling the event due to the threat of protestors. Milo canceled on us due to the fact that we could not meet his accommodations."
A similar event at UC Davis was also canceled.
The 32-year-old Greek-born British journalist is a senior editor for the conservative news and opinion website. He's been called a spokesperson for the so-called "alt-right" movement for his extreme views on Islam, social justice, and political correctness.
He's a self-proclaimed "internet troll" who has been widely criticized for being racist and misogynistic.
Passions started flaring around 4 p.m. between both sides on the Cal campus ahead of Yiannopoulos' 8 p.m. speech. The event is sponsored by the Berkeley College Republicans. Extra police officers were called to monitor the event.
The protests turned violent shortly before 5 p.m. as the event approached, with demonstrators lighting fires and fireworks on the Cal campus.
Yiannopoulos spoke Monday night at Cal Poly in San Luis Obispo, where he drew a diverse crowd of opponents and supporters. Cal State police monitored the crowd closely. The sold-out event was sponsored by the Cal Poly chapter of the College Republicans and not by the university itself.
He has yet to step foot on campus, but the famous provocateur is stirring debate and prompting protests at Berkeley.
The barricades are up for the crowds expected ahead of Yiannopulous' speech.
"We're doing this because we feel like we want to exercise our free speech," said President of the Berkeley College Republicans Jose Diaz. "We want to bring someone here on campus to help speak on issues that sort of opens the dialogue."
But there are many others who believe Yiannopulous' rhetoric is hateful, even dangerous, and has no place on a public university campus.
"Chancellor Dirks in his statement said the Constitution does not allow him to restrict free speech, and that's not true," said protest organizer Mukund Rathi. "Universities restrict free speech all the time for educational and security reasons."
Last month, Yiannopoulos' planned appearance at U.C. Davis was canceled at the last minute due to security concerns.
U.C. Berkeley officials told ABC7 News they have outside police agencies ready if necessary to keep the same sort of scene from forming at Berkeley.
"We are confident that we have the plan and the pieces in place," said Dan Mogulof of UC Berkeley. "The law, ample court precedent, and the Supreme Court could not be clearer that this event is fully and completely protected by the first amendment."