Steven Boone, 31, was also convicted in an Ottawa court of three counts of aggravated sexual assault by administering a noxious substance, which prosecutors identified as his semen, the Ottawa Citizen reported.
The jury heard Boone learned he was HIV positive in October 2009. His convictions date to December 2009 through April 2010, the report said.
He was charged in 2010 when a 17-year-old man told police he'd had unprotected sex with Boone and he was now HIV positive, the Canadian Broadcasting Corp. said.
Crown prosecutors introduced an online chat record in which Boone bragged he'd "lost count" of the number of partners with whom he'd had sex without a condom, the newspaper said.
When the jury announced their verdicts, Boone began crying and told his lawyers, "There is no way I was trying to kill anyone."
Sentencing is being delayed until Boone is tried on similar, but separate charges Nov. 13.
He also faces similar charges in Waterloo, Ontario, northwest of Toronto, the CBC said.