Activists and state-aligned media reported a judge handed down the verdict Thursday, saying 18 defendants received life sentences, while the other eight received 15-year sentences.
Those sentenced belonged to a group called Diraz Youth. The town of Diraz is home to a prominent Shiite cleric who has also been stripped of his citizenship and received a 1-year suspended prison sentence.
The trial comes amid a yearlong crackdown on dissent in Bahrain targeting political parties, activists and others.
Independent news gathering in Bahrain has grown more difficult, with the government refusing to accredit two Associated Press journalists and others.
Bahrain is home to the U.S. Navy's 5th Fleet and an under-construction British naval base.