The Transocean Winner rig ran aground at Dalmore on Lewis in a storm while being towed to the Mediterranean.
It was later refloated and anchored at Broad Bay before being put on board the heavy lift ship Hawk nearly three weeks ago.
The rig will be repaired and stripped of fittings in Malta before being taken to Turkey to be scrapped.
The rig's grounding on 8 August sparked pollution fears due to the 280 tonnes of diesel on board.
Investigations found two of its four fuel tanks were damaged in the incident which resulted in the loss of 53,000 litres of fuel, most of which is thought to have evaporated with no damage to the environment.
Three weeks later it was towed to the safer anchorage at Broad Bay before being floated on to the deck of the Hawk, a semi-submersible ship used for transporting large maritime structures over long distances.
A 17,000-tonne oil rig which ran aground on the Western Isles in early August has arrived in Malta.