It took a jury a little over three hours to find Darrell Brooks guilty of all 76 charges, including six counts of first-degree intentional homicide.
He faces a mandatory life sentence on each homicide count over the Milwaukee, Wisconsin, attack.
Brooks, dressed in a suit and tie, silently rested his head on folded hands as the verdicts were read. His subdued demeanour was a stark departure from previous days of the trial, when his sometimes outrageous behaviour drew rebukes from the judge.
Judge Jennifer Dorow scheduled a hearing on Monday to set a sentencing date.
Victims and their families are expected to make statements then.
Brooks drove his Ford Escape into the Christmas parade in Waukesha, suburban Milwaukee, on November 21, moments after fleeing a domestic disturbance with his ex-girlfriend, prosecutors said.
Six people were killed - including eight-year-old Jackson Sparks, who was marching in the parade with his baseball team - and three members of the Dancing Grannies, a group of grandmothers that dances in parades. Scores of others were hurt, some severely.
Laurie Hogeland, a friend of some of the parade victims, told reporters outside the courthouse after the verdict that justice had been served.
“It was a brief moment of relief,” she said. “But, then all the pain comes back. The pain comes back.”
Brooks pleaded not guilty by reason of mental disease earlier this year but withdrew the plea before his trial began with no explanation.
Days before the trial started, he dismissed his public defenders, electing to represent himself despite overwhelming evidence against him.
Police officers and paradegoers testified they saw Brooks behind the wheel of the SUV. District attorney Susan Opper presented several photos of Brooks driving the vehicle to the jury.
Brooks’ main defense theory appeared to be that he was a sovereign citizen, echoing a conspiracy theory that every person is a nation and isn’t subject to government restrictions. He refused to recognise the court’s jurisdiction over him, refused to answer to his own name, launched into meandering cross-examinations, and muttered under his breath that the trial wasn’t fair.
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He got into daily arguments with the judge that often devolved into shouting matches. At one point he glared at Judge Dorow so intensely she had to take a recess because she said she was scared of him.
Multiple times, she moved him into another courtroom where he could watch the proceedings via video and she could mute his microphone when he became disruptive.
One day, after he was moved to the other room, he stripped off his shirt and sat bare-chested on his table with his back to the camera. On another day, he built a barricade out of his boxes of legal documents and hid behind it.
Ms Opper told jurors during her closing arguments Tuesday that Brooks’ refusal to stop once he entered the parade route shows he intended kill people.
Judge Dorow allowed Brooks back into the main courtroom to deliver his closing statement to jurors face to face.
In a rambling, repetitive speech, he tried to raise doubts about whether the SUV’s throttle malfunctioned and whether the driver simply panicked. He lamented how he hasn’t been able to see his children since he was arrested and insisted he’s not a murderer.
Ms Opper countered during her rebuttal that a Wisconsin State Patrol vehicle inspector testified earlier that the SUV was in good working order. She warned jurors that Brooks was just trying to play on their sympathy.