A jury in Los Angeles convicted the 30-year-old Canadian of felony negligent discharge of a firearm, assault with a semi-automatic firearm, and carrying a loaded and unregistered firearm.
He faces more than 20 years in prison.
Megan Thee Stallion, a 27-year-old Grammy-winning rapper, earlier testified that she was shot in the feet after leaving a pool party.
Lanez showed no reaction as the verdict was read out. He was remanded in custody and is due to be sentenced on 27 January.
It was not immediately known whether he planned to appeal.
Speaking after the case concluded, one of Megan Thee Stallion's lawyers told reporters "the jury got it right. I am thankful there is justice for Meg". The rapper was not in court to hear the verdict.
During the trial, Megan Thee Stallion, whose real name is Megan Pete, testified that she was shot and wounded at the party in the Hollywood Hills on 12 July 2020.
The rapper argued that Lanez, whose real name is Daystar Peterson, became enraged after she had disparaged his musical talent. She said she had demanded to be let out of a luxury car before he fired five rounds at her.
She told the jury the Canadian had told her to "dance" before opening fire.
Megan Thee Stallion: How the shooting got to trial Megan Thee Stallion 'scared' after 2020 shooting What we know about Megan Thee Stallion 'shooting'
She also testified that he had offered her $1m (£830,000) to keep quiet about the attack because he claimed to be on probation for a weapons offence. She initially said to police that she had cut her feet on glass.
Lanez denied the charges relating to a dispute with the fellow artist and his lawyer, George Mgdesyan, unsuccessfully argued that the investigation had been botched.
He said it was Megan Thee Stallion's friend Kelsey Harris who had shot her, adding that it was all about "jealousy".
Several bullet fragments were removed from Megan Thee Stallion's feet after the shooting, but some remain.
She also acknowledged in her testimony that she had been "intimate" with Lanez.
Megan Thee Stallion - who won a Grammy for best new artist in 2021 - is best known for her hit Savage, which features Beyoncé.