It is believed he suffered a heart attack at home on Saturday morning.
Mr Meehan, a major figure in the IRA in the Ardoyne area of north Belfast during the Troubles, was a Sinn Fein councillor in Antrim.
Sinn Fein assembly member Gerry Kelly said he was "shocked and saddened" by the death, and said his thoughts were with Mr Meehan's family.
"From a friendship and comradeship point of view, Martin sort of embodied what republicanism was all about," Mr Kelly said.
"He gave his whole life to serve both his ideals in republicanism and also the people."
Mr Meehan had unsuccessfully stood in the South Antrim constituency in assembly and Westminster elections for Sinn Fein in recent years.
He was seen as a strong supporter of the Gerry Adams and Martin McGuinness leadership of the party.
Mr Meehan joined the IRA in 1966 and sided with the Provisional IRA faction when it split four years later.
In the weeks that followed the introduction of internment without trial in Northern Ireland in 1971, Mr Meehan was reputed to be the most wanted IRA man in Belfast.
He was eventually detained in Crumlin Road prison.
He escaped with two other IRA men in 1971 by hiding in a manhole for six and a half hours.
Mr Meehan fled to Dundalk in the Irish Republic and was arrested south of the border in 1972 with seven colleagues after a major four-hour gun battle over the border with a British Army platoon.
He returned to Northern Ireland and spent three years in prison.
The north Belfast republican had other jail terms before he was eventually released in January 1994.
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