Tamang, an assistant general secretary of the party, was unanimously elected as the CEO by 34 of the 45 GTA members at a close door meeting, GTA chairman, Pradip Pradhan told a press conference here.
Ten GTA members, who were in jail with cases against them, could not turn up for the election.
Tamang, who was arrested on August 22 for arson at a government bungalow at Chakdah and for blocking a highway during the GJM movement besides other cases registered against him in 2007, took oath as the CEO after his release from judicial custody during the day.
After the GJM said it wanted dissolution of the GTA, West Bengal Chief Minister Mamata Banerjee had proposed that the government would accept any GTA member as the CEO.
Bimal Gurung had resigned as GTA CEO on July 30 before GJM called a series of bandhs in the hills.