During the 20-day trial the court heard how Henry Chau, 31, had dismembered his elderly parents before salting, cooking and packing their body parts into lunchboxes "like barbecued pork".
The severed heads of 65-year-old Chau Wing-ki and his wife Siu Yuet-yee, 62, were found in March 2013, stuffed into two refrigerators in a bloodstained apartment, days after they were reported missing.
Other remains were found in a rubbish bin and packed into lunchboxes with rice.
A jury at the city's high court found Chau guilty on both counts of murder by a majority of 8-to-1, the South China Morning Post reported.
More From This Section
Both had pleaded not guilty to the charges.
Chau will be sentenced on Monday, the Post reported.
Chau initially told police that his parents had gone to mainland China, but later admitted to the murder on an Internet messaging group.
In evidence read to the city's High Court last year, Chau claimed that he planned to mislead the police in order to buy himself some time to say goodbye to friends.
"My murdering partner and I were planning to make it a missing person case and dump the body piece by piece," he said in a group message.