The jail terms were handed to 12 members of the "Movement for Muslim Unity", a Shiite opposition group, by a court in the oil-rich country's capital Baku.
The group's lawyer Fariz Namazly told AFP the men were found guilty of "an attempt to take power, terrorism, preparation of mass unrest and other serious crimes".
The group reject the charges and claim they were tortured and coerced in to giving confessions while in detention, the lawyer added.
Among them was the deputy chairman of the Popular Front party Fuad Gahramanly, who was sentenced to 10 years in prison on charges of inciting religious hatred and mass unrest.
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Azerbaijan has accused the Movement for Muslim Unity of aiming to establish a sharia state in the ex-Soviet country, which is secular but has a Shiite Muslim majority.
President Ilham Aliyev has ruled Azerbaijan since 2003. He succeeded his father Heydar Aliyev, a former KGB officer and communist-era leader who had ruled the country with an iron fist since 1993.