If found guilty in the court proceedings expected later this year, Bolsonaro could face a long prison sentence, isolating the firebrand who has avoided naming a political heir.
In his opening remarks on Wednesday, Justice Alexandre de Moraes, who is overseeing the case, screened dramatic footage of Bolsonaro's supporters storming government buildings in scenes that unfolded just a week after the inauguration of President Luiz Inacio Lula da Silva in January 2023.
Moraes cast the violence as the result of Bolsonaro's "systematic effort" to discredit the election he lost and then conspire to overturn using violence, with the help of senior military officers and cabinet members.
Bolsonaro, a former army captain who served as Brazil's president from 2019 to 2022, is accused of five crimes, including an attempt to violently abolish the democratic rule of law and a coup d'etat.
He has denied any wrongdoing and denounced the case as politically motivated.
The Supreme Court began reviewing charges against Bolsonaro and seven close allies in a Tuesday session he voluntarily attended, sitting silently in the first row.
Wednesday's ruling, roughly a month after Brazil's top prosecutor presented charges, reflected an extraordinary pace for a top court that often takes years to decide major cases.
The speed reinforced views that the justices are keen to wrap up the trial before the 2026 presidential campaign gets underway.
Bolsonaro has insisted he will run for president again next year, despite a ruling by Brazil's Superior Electoral Court that barred him from running for public office until 2030 for his efforts to discredit the country's voting system.
Ahead of the landmark court hearing, Bolsonaro called a beachfront rally in Rio de Janeiro, hoping to seize on Lula's waning popularity and pressure Congress to pass an amnesty bill favouring him and his jailed supporters.
The demonstration, which some allies suggested could draw more than a million backers, was widely considered a flop after two independent polling firms suggested that between 20,000 and 30,000 people showed up.
"There are two trials: the first against the accused and the second about the Supreme Court itself," said Leonardo Barreto, a partner at Brasilia-based consultancy Think Policy.
Bolsonaro's allies in Congress, where conservative politicians have voiced concerns about overreaching by the court, are unlikely to abandon him, Barreto said, adding that "he has something all politicians value the most, which is votes".
