The sentence would disqualify Pashinian from a general amnesty that was declared by the Armenian authorities in June.
It would also effectively invalidate his chances of victory in a January 10 by-election to the National Assembly.
The editor in chief of the "Haykakan Zhamanak" newspaper was registered as a candidate for the election earlier this month despite being under arrest and on trial.
The lengthy jail term was demanded on December 22 after Mnatsakan Martirosian, the presiding judge, declared an end to the cross-examination of the defendant and witnesses and proceeded to the final phase of the trial.
The final indictment was then read by prosecutors.
Koryun Piloyan, another prosecutor, told RFE/RL that their final speech was essentially drawn up "several days ago."
Defense lawyers, meanwhile, presented additional evidence and video materials relating to the March 2008 clashes between opposition protesters and security forces.