The 700,000sqm new terminal and 400,000sqm of related GTC encompass more than 1.1 million square metres of floor area at the international gateway to the historic city of Xi'an.
The competition entry against other international consortiums was a global effort led by L&B's China office and supported by Chinese partners and L&B architectural design staff from studios in Australia and the USA.
L&B will provide the ongoing leadership of the architectural design services for this major programme supported by other team members including North West Design Institute, Chinese Architectural Design Institute and other specialists.
As the eighth busiest airport in China, Xi'an Xianyang International Airport handled 37 million passengers in 2016 through its existing terminals.
At the completion of the next phase of development, the airport will have four parallel runways and the East Terminal will handle up to 40 million passengers per annum.
Ultimately, the airport is projected to serve 120mppa with a five-runway system.
In announcing the selection, the judges commented that L&B's entry was "a most balanced, comprehensive, compatible and flexible scheme."
Xiang Huang, associate vice president of L&B, commented: "I believe this competition success and the ongoing design role is further acknowledgement of the value that clients see in harnessing our specialist integrated skills across airport planning and terminal design and I am immensely proud of the achievement of our team."