The ransom, also one of the largest ever paid, sparked a deadly feud within the group of pirates delaying the release of the ship and its crew of 28 seamen who were taken in the Indian Ocean on November 29.
"She's free. She's preparing to sail out'' from the pirate lair of Harardhere, Andrew Mwangura of the East African Seafarers Assistance Program said today.
Pirate sources in Harardhere said the huge ship was still anchored off Harardhere today apparently receiving last-minute technical assistance from a nearby foreign warship.
Ecoterra International, an environmentalist NGO that monitors illegal maritime activity in the region, said the last pirates left the very large crude carrier (VLCC) early today.
It added that pirates reportedly bragged about generously giving $US500 ($543) to each crew member - 16 Filipinos, nine Greeks, two Ukrainians and a Romanian - "for good co-operation''.
On December 2, the 332-metre-long ship was brought to the pirate base of Hobyo but was subsequently moved further south to Harardhere, the capital of Somali piracy.
The 1995-built supertanker, the second largest vessel seized by Somali pirates yet, is carrying two million barrels of crude, which is equivalent to the daily output of some of the world's top oil producers.
The largest snatched by Somalia's marauding freebooters was the Sirius Star, a Saudi-owned VLCC seized in 2008, for which an estimated $US8 million ($8.68 million) were paid in ransom money.
The hijacking of the Sirius Star sent shockwaves through the shipping world as pirates showed they could disturb key interests on one of the world's busiest maritime trade routes.
The incident also raised fears that pirates might one day use a hijacked ship as a weapon to carry out an attack and cause unprecedented human and environmental damage.
The ship, the first known case of a Greek-flagged vessel being hijacked, was headed from Saudi Arabia to the US.
The 300,000-tonne (deadweight) supertanker, hijacked by nine pirates, was easy prey for pirates equipped with fast skiffs and grapnels as it moves slowly and could not outmanoeuvre the nimble sea-robbers and has a low freeboard.