Omar Al-Kutobi, 25, and Mohammad Kiad, 27, had previously pleaded guilty to preparing for a terrorist act over their failed plot.
New South Wales Supreme Court Justice Peter Garling said both men were equal participants in the plot, which was thwarted when police raided their home in Feburary 2015.
Officers found a hunting knife, a machete and a homemade flag associated with the Islamic State group. Then-Prime Minister Tony Abbott said at the time that police also seized a video in which one of the men threatened to stab the kidneys and necks of their victims.
They will be eligible for parole in 15 years.