Auckland Airport says its $15.5 million extension is an important stepping stone towards building another runway.
Taxiway Lima opened on Tuesday and allows twice as many aircraft to use the western side of the international terminal building. The 1.2-metre-thick, 650-metre-long extension took nine months to build.
Airport chief executive Adrian Littlewood said it is an important step towards developing a northern runway, which construction will start on early next decade.
Mr Littlewood said the taxiway would reduce aircraft congestion and delays and also improve safety and efficiency, resulting in less waiting time for international passengers.
The opening was marked with a blessing of the taxiway, with an Air New Zealand plane then making its first trip down it.