A seventh was acquitted.
Friday's verdict brings and end to the long-running trial, which centered on the role played by Abu Salem -- who authorities accused of being a gangster -- in supplying weapons to the attackers.
The attacks, which occurred on March 12, 1993, remain the largest coordinated terror incident to have taken place on Indian soil in terms of the number of casualties, according to CNN affiliate News18.
Beginning at 1:30 p.m., the city -- then known as Bombay -- was rocked by a series of at least 12 coordinated blasts. Those explosions ripped through the heart of India's financial capital, destroying the stock exchange, the Air India building and other notable locations.
The bombings were ordered by Islamic militants in revenge for the demolition of Babri Masjid -- a 16th century mosque -- by Hindu extremists, the prosecution claims.
The destruction of the Babri Masjid in the town of Ayodhya in Northern India sparked a wave of religious violence that left hundreds dead across India.
Salem was extradited from Portugal in 2005 on numerous criminal charges. In February 2015, he was sentenced to life in prison for the 1995 murder of Mumbai builder Pradeep Jain.
On Friday, Salem was convicted of conspiracy and terror activities. He was also found guilty under the Arms and Explosives Act for procuring and supplying weapons, according to Special Public Prosecutor Deepak Salve.
Some of those arms were supplied to Bollywood actor Sanjay Dutt, who was found guilty of acquiring illegal weapons tied to the attack. He was released in 2016 after serving a five-year prison sentence.
The others convicted include Mustafa Dossa, Firoz Khan, Tahir Merchant, Riyaz Siddiqui and Karimullah Khan. Their charges range from criminal conspiracy, waging war against the Indian government and murder under sections of the Indian Penal Code and the Indian Explosives and Explosive Substances Act.
A seventh accused, Abdul Qayyum, was acquitted and the court ordered his immediate release.
Sentences could be announced when the court reconvenes.
Friday's conviction is the second trial connected to the bombing. The first, which concluded in 2007, led to the convictions of 100 people, including key conspirator Yakub Memon. He was sentenced to death. Ten others were also given the death penalty, but later appeals reduced their sentences to life in prison in 2013.