Ishaq Hajwane was at present out on bail. The Supreme Court had upheld his conviction by TADA court in March this year.
He was one of the convicts who along with actor Sanjay Dutt had been given one-month additional time to surrender by the apex court.
"Ishaq Hajwane died at his residence. He was suffering from multiple organ failure," said his advocate Farhana Shah.
Hajwane was found guilty of criminal conspiracy and participating in a weapons training session organised by Tiger Memon, the key mastermind behind the blasts.
Hajwane was to surrender on May 16, Shah said.
"I will inform the court about his demise to the TADA court once I get the death certificate," Shah added.