Juliano Verbard, 27, serving a 15-year term, and two followers, were pulled on to the helicopter by three accomplices.
The accomplices had pretended to be tourists when boarding the helicopter, but then forced the pilot to land in the prison grounds before flying off.
They then landed a few hundred metres away, and drove off in a waiting van.
The island's police force said a major search was now under way for Verbard and his fellow prisoners, Alexin Jismy and Fabrice Michel.
Verbard, the leader of the pseudo-religious cult, the Sorrowful and Immaculate Heart of Mary, was jailed in 2008 for rape and sex attacks on children, and the other two for their roles in a kidnap.
At the time of his trial, psychiatrist Gerard Toulfayan described Verbard as an "extremely powerful manipulator with great intelligence".
The two helicopter crew members were unhurt.
The pilot later told a local radio station about the hijacking: "One of them put a gun to my temple while another threatened to set fire to a bottle of petrol he had in his hand with a cigarette lighter."
"You see, they had nothing more to lose. They were ready to blow it up, ready to die."
This is nuts, how many action movies were watched before this idea was hatched?