RIO DE JANEIRO — The former president of Brazil, Luiz Inácio Lula da Silva, was found guilty of corruption and money laundering on Wednesday and sentenced to nearly 10 years in prison, a stunning setback for a politician who has wielded enormous influence across Latin America for decades.
The case against Mr. da Silva, who raised Brazil’s profile on the world stage as president from 2003 to 2010, stemmed from charges that he and his wife illegally received about $ 1.1 million in improvements and expenses from a construction company for a beachfront apartment.
In exchange, prosecutors said, the company was able to obtain lucrative contracts from Petrobras, the state-controlled oil giant.
His conviction tarnishes the legacy of one of Brazil’s most commanding political figures, a charismatic leader who grew up poor, challenged the military dictatorship and nurtured global ambitions for his nation, helping to land the 2014 World Cup and the 2016 Olympics.
“This goes far beyond himself and his political career, which is seriously damaged. It’s Brazil’s reputation,” said Christopher Sabatini, executive director of Global Americans, a research group in New York. “He was a brand. Brand Brazil.”
But Brazil’s economic fortunes eventually turned and, plagued by scandals, Mr. da Silva’s leftist Workers’ Party lost the presidency last year when the Senate impeached his handpicked successor, Dilma Rousseff, in a power struggle that consumed the nation.
Mr. da Silva, 71, who has called the charges against him a “farce,” has been planning a political comeback. Despite multiple corruption allegations against him, he has announced his intention to run for president in next year’s election and has been widely considered a leading contender.
The ruling could be a crippling blow to his aspirations.
Judge Sergio Moro, who issued Wednesday’s verdict, said that under Brazilian law, Mr. da Silva would be ineligible to run for office for twice as long as his sentence, or 19 years.
Legal scholars interpreted the ruling to mean that Mr. da Silva could still run for president while the case is being appealed. But if he fails on appeal, they said, it could either leave the Workers’ Party without an obvious candidate in next year’s vote or prevent him from taking office.
The conviction is the latest salvo by Brazil’s judicial branch, which has declared war on the country’s entrenched culture of corruption. Brazil’s current president, Michel Temer, was charged last month with corruption, part of a near constant stream of allegations and charges that have ripped through the nation’s political establishment in recent years.
Judge Moro, who oversees cases stemming from a broad graft scandal surrounding the state-controlled oil company, said Mr. da Silva’s actions were part of a “scheme of systemic corruption” at Petrobras.
“The president of the republic has enormous responsibilities,” Judge Moro wrote. “As such, his culpability is also” enormous when he commits crimes, he added.
Mr. da Silva presided over a period of robust economic growth in Brazil and remains a widely popular figure, credited with leading a social transformation that lifted millions from poverty in a nation with one of the world’s biggest disparities between rich and poor.
Despite the corruption allegations against him and his party, Mr. da Silva has been leading in recent public opinion polls on the election. Judge Moro, the judge who convicted him, is often cited as Mr. da Silva’s closest rival in hypothetical matchups in the presidential race, though Judge Moro has ruled out running for office.
“We view this as an attempt to push Lula out of the electoral process,” said Senator Gleisi Hoffmann, who recently took the helm of the Workers’ Party. “A presidential election without the participation of Lula is fraudulent and undemocratic. If you want to take him out of the running, then put up a candidate and run against him in the electoral booth.”
Mr. da Silva’s lawyers said in a statement issued Wednesday night that the former president is innocent. They called him the victim of a politicized prosecution, “a famous strategy that has been used to brutal effect by various dictatorships throughout history.”
In the verdict, the judge said that the former president had sought to intimidate the court, which the judge argued could be grounds for ordering his immediate arrest. Yet Judge Moro deemed it “prudent” to allow Mr. da Silva to remain free pending an appeal.
Sending a former president to jail would be a “traumatic” event, he wrote.
While Mr. da Silva’s conviction involves relatively modest sums, especially compared with the staggering scale of some corruption cases in Brazil, prosecutors have described him as the mastermind of an enormous kickback scheme that enabled his party to buy support in Congress.
The case against him began with an investigation into money laundering at a gas station. But as prosecutors continued digging, they said they discovered billions of dollars’ worth of bribes involving Petrobras and powerful contractors like Odebrecht, a large construction company with deep ties across the hemisphere. The case — which became known as the Lava Jato, or Car Wash, scandal — has ensnared other powerful politicians and put dozens of lawmakers under a cloud of suspicion.
Eduardo Cunha, the former speaker of the House, was sentenced in March to 15 years in jail for money laundering and corruption uncovered during the Petrobras investigation. And Mr. Temer, the current president, is working furiously to avoid being put on trial, hoping to persuade lawmakers not to send the charges against him to the Supreme Court, the only venue where senior sitting politicians can be prosecuted.
The investigations have left Brazilians with few prominent politicians untainted by allegations of corruption. Wary politicians, meanwhile, have been considering passing an amnesty law to shield themselves, arguing that such protection is warranted to avert a collapse of the political system.
Mauricio Santoro, a political scientist at the Rio de Janeiro State University, called the sentence against Mr. da Silva a momentous turning point in a deeply polarized nation.
“We have almost half of the country wanting Lula to be president and the other half wanting him jailed,” Mr. Santoro said. “This puts a huge responsibility in the hands of the judges” ruling on the appeal.
Even if Mr. da Silva wins the appeal, he said, the case adds to the sense that Brazil’s crusading judiciary has changed the rules of the game for politicians. Past presidents widely suspected of corruption managed to keep prosecutors at bay.
“We are living in a very different Brazil,” he said.