Ballymena's Wrightbus bus manufacturer has won an order to supply 300 fuel efficient vehicles to a major UK operator.
FirstGroup expects to cut the cost of fuel bills on the new machines by a tenth.
Wrightbus in Co Antrim in Northern Ireland has enjoyed massive success in recent years and managing director Mark Nodder said: "This is further great news for Wrightbus and the Northern Ireland economy.
"Hot on the heels of last year's order to build 600 innovative double deck buses for Transport for London, this order for FirstGroup will help secure existing jobs right across our business."
FirstGroup has ordered 301 Wrightbus StreetLite buses, 274 of which are specified with innovative "micro hybrid" technology, developed exclusively by the Ballymena based-company.
Micro hybrid technology captures the energy generated from a bus's braking system, and redistributes this energy.
The result is a reduction in fuel consumption of up to 10%, leading to substantial savings over a bus's typical 15-year operational service life.
Managing director of First UK Bus (a division of FirstGroup) Giles Fearnley said: "Our groundbreaking partnership with Wrightbus will deliver unsurpassed levels of fuel efficiency. In 2013 we laid down the gauntlet to bus manufacturers to work with us to minimise fuel consumption.
"Wrightbus embraced that challenge and together we've developed its StreetLite Micro Hybrid product."
The chassis for the new buses will be built at Wrights Group subsidiary EN-Drive in Antrim. The bodywork will be assembled in Ballymena.
Vehicle deliveries will start during the next few months, with all buses expected to be in full operational service by early 2015.
A FirstGroup statement said it was part of a £70 million investment in 425 new buses, helping to improve reliability, reduce fuel and maintenance costs.