Lawyers for the jailed young men told RFE/RL on September 13 that the new charges were organization of mass disorders and taking part in them.
The eight were arrested in March and April on charges of possessing illegal drugs and weapons after they took part in an antigovernment protest in Baku in March.
The activists deny any wrongdoing, saying the charges against them are politically motivated.
New York-based Human Rights Watch accused the Azerbaijani authorities last week of trying to silence dissent ahead of the October 9 presidential election.
In August, Amnesty International demanded the immediate release of the activists, saying the Azerbaijani government has a record of pressing false charges to silence dissent.