Bernardo, 31, a former bookkeeper, was accused of abducting the girls in separate episodes in 1991 and 1992, forcing them to be sex slaves in front of a video camera and then strangling them. He received concurrent life sentences on the murder charges. Sentencing on the other charges is to be discussed on 15 September.
Bernardo admitted that he and his then wife, Karla Homolka, abducted Leslie Mahaffy, 14, and Kristen French, 15, and abused them. He denied killing them, suggesting they died accidentally or during escape struggles with Homolka while he was not present.
The videos Bernardo and Homolka shot of the abuse, which became key evidence, showed Bernardo raping, beating and humiliating the girls, but not killing them.
Homolka, 25, said Bernardo strangled the girls with a cord. She did a deal to testify against Bernardo and plead guilty to manslaughter, and is serving a 12-year term.
The jury deliberated for seven hours before finding Bernardo guilty of two counts each of murder, kidnapping, forcible confinement and aggravated sexual assault, and one count of committing an indignity to a body.
Spectators at the trial could hear, but not see, the videos shown to the jury. Some of those in court daily covered their ears to block out the girls' anguished screams.
Homolka testified that she was beaten and blackmailed into taking part in Bernardo's depraved sex fantasies.