Saudi officials said on Wednesday that one person had been sentenced to death in the trials, but gave no details of the other verdicts.
Saudi Arabia has said the trials involved "membership of a deviant group of people and involvement in their activities and supporting and financing of terrorism".
Officials usually use "deviant group" as a reference to members of anti-government groups, including al-Qaeda.
Prince Nayef bin Abdul-Aziz, the Saudi interior minister, said in October that the kingdom had charged 991 mainly Saudi suspected al-Qaeda members with carrying out 30 attacks since 2003.
A group called al-Qaeda in the Arabian Peninsula began a campaign to destabilise the government in 2003, but the violence was brought to a halt by security forces in co-operation with foreign assistance.
Attacks included suicide bombs at housing compounds in the capital, Riyadh, in 2003 and an attempt to storm the world's biggest oil processing facility at Abqaiq in 2006.
Authorities have arrested hundreds of suspects over the last two years on suspicion of trying to revive al-Qaeda-linked cells.