Ballymena bus maker Wrightbus has landed a £30 million deal to supply 415 buses to Singapore.
The double-deckers will be sent as kits, before being assembled with support from the company's technicians.
It comes after Wrightbus secured another major £41 million deal in the country two years ago.
The Co Antrim manufacturer is now the main supplier of double-deckers for SBS Transit - Singapore's public transport operator.
In 2012 the firm secured a three-year contract to supply 550 buses to Singapore.
Enterprise Minister said the latest demand for its kits had "created significant opportunities for the business".
"This substantial contract secures Wrightbus as the primary suppliers of double-deck buses for SBS Transit, a subsidiary company of the ComfortDelGro Corporation, into 2017," she said.
"It follows three previous orders with the same company, resulting in over 1,000 similar vehicles entering service with SBS Transit since 2010.
In 2009, Wrightbus was commissioned by London Mayor Boris Johnson to build a cleaner and more efficient 21st century version of the Routemaster – London's iconic red double-decker bus. The so-called 'Boris Bus' began service in 2012 and 600 of the hybrid buses have been ordered.