The case centered on a bomb attack that left three police officers dead on March 3, 2014 as they were dispersing "rioters and vandals" on the outskirts of the capital Manama, according to authorities.
One of those killed was a police officer from the nearby United Arab Emirates who was deployed to help bolster security in the tiny island kingdom.
The eight defendants who escaped the death penalty were sentenced to life imprisonment and will have their citizenship stripped, defense attorney Mohammed al-Tajir was quoted by AP as saying. He said he will appeal the verdict.
Bahrain is a Western-allied kingdom off the coast of Saudi Arabia that is home to the US Navy's 5th Fleet.
The Persian Gulf state has been the scene of an ongoing clampdown on anti-regime protesters.
The uprising in Bahrain began on February 14, 2011. Protesters initially called for political reforms and a constitutional monarchy. However, the demand later changed to an outright call for the ouster of the Al Khalifa family following its deadly crackdown on popular protests.
Scores of people have been killed in the crackdown and security forces have arrested hundreds including doctors and nurses. Dozens of demonstrators have also been sentenced to jail terms for attending street protests.