The verdict against Serge Pomerleau, Yves Denis and Denis Lefebvre was handed down in Quebec City after the jury of six men and six women had deliberated for several days.
The criminal case was already ongoing against the three when a chopper airlifted them from the detention centre courtyard in June.
They became the subject of an international manhunt and an Interpol red alert.
All three were captured two weeks later in a luxury Montreal condo.
Sentencing arguments will begin Nov. 17.