Mamumiyan Panjumiyan was arrested in 2008 for allegedly providing the AK 47 rifle used in the offence.
Abdul Latif, main accused in the case, died in an encounter with the police.
The gang members, allegedly bootleggers, killed nine persons in a shoot-out at Radhika gymkhana situated in Odhav locality in 1992.
Sessions judge H J Joshi acquitted Panjumiyan after the prosecution failed to provide any evidence against him.
In 2009, the court had awarded life sentence to eight persons and a seven-year jail term to another, while 13 others were acquitted. Five of the accused died during the trial while two are absconding.