Engineering company Babcock said it lifted the structure, which weighs more than 600 tons, onto the flight deck of the carrier under construction at its shipyard in Rosyth, Scotland.
The forward island -- about 72 feet high, 42.6 feet wide 42.6 feet long. -- will house the ship's main bridge and about 100 system compartments.
"Seeing the forward island in position on the flight deck marks a highly visible achievement in the assembly program," said Babcock QEC Project Director Sean Donaldson.
"The month for lifting the island into place was set over three years ago. Since then the island has been designed and constructed, the crane put into place and the blocks that the island sits on assembled ready to accept the island -- a considerable achievement."
Babcock said system consoles have already been installed in the structure, as well as cables and pipes.
The carrier is three-quarters completed and is expected to leave the shipyard next year for sea trials.