First Additional District and Sessions Judge Rajiv M Apte acquitted Pragya, Harsh Solanki, Vasudev Parmar, Ramcharan Patel, Anandraj Kataria, Lokesh Sharma, Rajendra Choudhary and Jitendra Sharma, saying there was not enough evidence against the accused to nail them in the murder.
Joshi was shot dead here on December 29, 2007.
Initially, the probe had hit a dead-end, but later arrest of a person in Rajasthan led the district police to name Pragya and others as accused in the case.
Joshi was once a close aide of Pragya, but they fell out later.
Pragya is in judicial custody in connection with terror cases. She was not present in the court here when the verdict was announced.
Hearing the not guilty verdict, Anandraj and Vasudev, who were present in the court along with relatives and supporters, broke down.