The judge ruled he could remain free pending an appeal.
Lula has rejected claims that he received an apartment as a bribe in a corruption scandal linked to state oil company Petrobras.
He says the trial is politically motivated and has strongly denied any wrongdoing.
The case is the first of five charges against him.
Lula served eight years as president until 2011 and has expressed interest in running again in next year's elections for the left-wing Workers' Party.
On Wednesday, a judge found him guilty of accepting bribes from engineering firm OAS in the form of a beachfront apartment in return for his help in winning contracts with the state oil company.
The head of the Workers' Party, Senator Gleisi Hoffmann, hit out at the ruling, saying it was designed to stop Lula standing for office.
She said the party would protest against the decision.
The BBC's Katy Watson in Sao Paulo says Lula remains a popular politician and the sentence will deeply divide Brazil.
The charges Lula faces all relate to the Car Wash scandal, the nickname for Brazil's biggest ever corruption probe.
Operation Car Wash was launched three years ago amid escalating public anger over political corruption.
The investigation centres on firms that were allegedly offered deals with Petrobras in exchange for bribes, which were funnelled into politicians' pockets and party slush funds.
Lula, a former steel worker turned union leader, came to office as the first left-wing leader in Brazil in nearly half a century.
He was Brazil's most popular president during his tenure - former US President Barack Obama labelled him the most popular politician on Earth.
Unable to stand for a third consecutive term, he was succeeded by close ally Dilma Rousseff, who was later impeached.
Current President Michel Temer also faces corruption allegations and is resisting calls for him to step down.