Mayor of London Boris Johnson is in Northern Ireland to open a manufacturing plant that will produce the chassis for the new London buses.
Wrightbus, a family-owned company in Ballymena, Co Antrim, will build 600 of the new vehicles over the next three years.
The order will see the workforce at the new chassis plant more than double from 40 people to 90 when full production gets started. The contract will also safeguard 220 jobs and sustain 18 apprenticeships.
"London's transport network is the supply line for new jobs and growth around the whole of the United Kingdom. We already support 40,000 jobs outside of the capital and we believe we can create more.
"The programme of transport improvements we want to see in the capital is bursting at the seams with job generation potential, and that is why protecting investment in London transport should be the Government's top priority as they consider how best to conduct this summer's spending review," said Mr Johnson.
The London Mayor will also visit the Wrightbus main factory to view the full production line.
The new bus is the greenest diesel electric hybrid bus in the world. It produces a quarter of the PM and NOx of the fleet average hybrid bus, and 20% less CO2.
As well as the manufacture of the chassis and superstructure in Northern Ireland, a number of components for the new bus are made by companies from around the UK; including engines from Darlington, seats from Telford, seat moquette from Huddersfield, wheelchair ramps from Hoddesdon and flooring from Liskeard.