Calling the video a clear threat to a lawmaker's life, Democrats argued Gosar's conduct would not be tolerated in any other workplace - and shouldn't be in Congress.
The vote to censure Gosar, and also strip him of his committee assignments, was approved by a vote of 223-207, almost entirely along party lines.
Republican Minority Leader Kevin McCarthy called the vote an "abuse of power" by Democrats to distract from national problems. He said of the censure, a "new standard will continue to be applied in the future," a signal of potential ramifications for Democratic members in future Congresses.
But Democrats said there was nothing political about it.
"These actions demand a response. We cannot have members joking about murdering each other," said House Speaker Nancy Pelosi. "This is both an endangerment of our elected officials and an insult to the institution."
Ocasio-Cortez herself said in an emotional speech, "Our work here matters. Our example matters. There is meaning in our service. And as leaders, in this country, when we incite violence with depictions against our colleagues that trickles down to violence in this country. And that is where we must draw the line."
MORE: GOP congressman Gosar under fire for cartoon attacking Ocasio-Cortez
Unrepentant, Gosar rejected what he called the "mischaracterization" that the cartoon was "dangerous or threatening. It was not."
"I do not espouse violence toward anyone. I never have. It was not my purpose to make anyone upset," Gosar said.
He compared himself to Alexander Hamilton, the nation's first Treasury secretary, celebrated in recent years in a Broadway musical, whose censure vote in the House was defeated: "If I must join Alexander Hamilton, the first person attempted to be censured by this House, so be it, it is done."
The decision to censure Gosar, one of the strongest punishments the House can dole out, was just the fourth in nearly 40 years - and just the latest example of the raw tensions that have roiled Congress since the 2020 election and the violent Capitol insurrection that followed.
The decision to move forward with the effort was born out of Democratic frustration with the House GOP, which declined to publicly rebuke Gosar, who has a lengthy history of incendiary remarks.
Instead, GOP leaders have largely ignored his actions and urged their members to vote against the resolution censuring him. They also warned that the effort sets a precedent that could come back to haunt Democrats if they find themselves in the minority,
Rep. Matt Gaetz of Florida said, "I would just suggest we have better things to do on the floor of the House of Representatives than be the hall monitors for Twitter."
The resolution will remove Gosar from two committees: Natural Resources and the Oversight and Reform panel, on which Ocasio-Cortez also serves, limiting his ability to shape legislation and deliver for constituents. It states that depictions of violence can foment actual violence and jeopardize the safety of elected officials, citing the Jan. 6 attack on the U.S. Capitol as an example.
Gosar becomes the 24th House member to be censured. Though it carries no practical effect, except to provide a historic footnote that marks a lawmaker's career, it is the strongest punishment the House can issue short of expulsion, which requires a two-thirds vote.
Democratic Rep. Charles Rangel, the former chairman of the powerful House Ways and Means Committee, was the last to receive the rebuke in 2010 for financial misconduct.
It would also be second time this year the House has initiated the removal of a GOP lawmaker from an assigned committee, the first being Marjorie Taylor Greene of Georgia.
Gosar, a six-term congressman, posted the video over a week ago with a note saying, "Any anime fans out there?" The roughly 90-second video was an altered version of a Japanese anime clip, interspersed with shots of Border Patrol officers and migrants at the southern U.S. border.
During one roughly 10-second section, animated characters whose faces had been replaced with Gosar, Greene and Rep. Lauren Boebert, R-Colo., were shown fighting other animated characters. Gosar's character is seen striking another one made to look like Ocasio-Cortez in the neck with a sword. The video also shows him attacking President Joe Biden.
Ocasio-Cortez, D-N.Y., whose receipt of repeated death threats has required her to spend thousands on security, said Gosar has not apologized to her. She singled out McCarthy for not condemning Gosar.
"What is so hard about saying this is wrong?" Ocasio-Cortez said on the House floor Wednesday. "This is not about me. This is not about Representative Gosar. But this is about what we are willing to accept."
Rep. Adam Kinzinger, R-Ill., was one of the few Republicans saying he would vote to censure Gosar.
"We have to hold Members accountable who incite or glorify violence, who spread and perpetuate dangerous conspiracies. The failure to do so will take us one step closer to this fantasized violence becoming real," Kinzinger tweeted.
This is not the first brush with controversy for Gosar, who was first elected in 2010's tea party wave. He has been repeatedly criticized by his own siblings, six of whom appeared in campaign ads supporting his Democratic opponent in 2018.
Earlier this year Gosar looked to form an America First Caucus with other hardline Republican House members that aimed to promote "Anglo-Saxon political traditions" while warning that mass immigration was putting the "unique identity" of the U.S. at risk. He's made appearances at fringe right-wing events, including a 2018 rally in London for a jailed British activist who repeatedly spread anti-Muslim views and a gathering in Florida last February hosted by Nick Fuentes, an internet personality who has promoted white supremacist beliefs.
He has also portrayed a woman shot by Capitol police during the attack on the Capitol as a martyr, claiming she was "executed." And he falsely suggested that a 2017 white supremacist rally in Charlottesville, Virginia, was instigated by "the left" and backed by billionaire George Soros, a major funder of liberal causes who has become the focus of anti-Semitic conspiracy theories.