Leighton Holdings has secured $1.2 billion worth of contracts linked to the $34 billion Ichthys liquefied natural gas project in Darwin.
The first contract, worth $923 million, is to build infrastructure such as roads, foundations and trenches, at Blaydin Point for Ichthys' onshore facilities.
Construction is due to start in May and be completed by July 2016, Leighton's wholly-owned subsidiary Leighton Contractors said in a statement.
It is the third project Leighton had won for Ichthys' onshore processing site.
Separately, the company said it had clinched a $280 million operations and maintenance contract for Blaydin Point's temporary facilities.
Leighton Contractors will operate and maintain services for all temporary site facilities, including power supply, water treatment plants and pest control, for more than four years during the construction phase.
The temporary facilities were currently being built by Leighton Contractors' infrastructure division.
"We see the LNG and coal seam methane markets offering significant opportunities for the Leighton Group, which has developed a high degree of competency in delivering essential infrastructure for large resources projects," Leighton chief executive Hamish Tyrwhitt said.
The Ichthys gas field lies about 200kms off the WA coast.
It is expected to produce 8.4 million tonnes of LNG and 1.6 million tonnes of liquefied petroleum gas a year.
Gas will be piped from the Ichthys field to Darwin, about 900km away, for processing and shipping.
Leighton shares were up 11 cents to $17.95 at noon.