"Given the violent events in Washington, DC, and increased risk of harm, we began permanently suspending thousands of accounts that were primarily dedicated to sharing QAnon content on Friday afternoon," Twitter said in a blog late on Monday.
"These accounts were engaged in sharing harmful QAnon-associated content at scale and were primarily dedicated to the propagation of this conspiracy theory across the service," the company said.
QAnon backers have pushed conspiracies on social media that include the baseless claim that Trump secretly is fighting a cabal of child-sex predators, among them prominent Democrats, figures in Hollywood and "deep state" allies.
Twitter had said on Friday it would permanently suspend accounts pushing QAnon content, banning prominent right-wing boosters of its conspiracy theories.
The storming of the Capitol building last week by Trump supporters delayed the certification of Biden's election victory.Lawmakers were forced to flee, as the building was mobbed by the president's supporters who overwhelmed security forces. Five people died in the violence including one Capitol Police officer who was beaten as he tried to ward off the crowds.