Bombardier in Belfast is to build parts for up to 142 business jets.
Vistajet, a private charter firm, has signed a deal worth more than £4.8 billion. This is the largest business aircraft sale in Bombardier's history and will help secure the jobs of around 5,500 people in Belfast.
A spokeswoman for the company said: "We in Belfast play a major role in the business jet sector - an important market which Bombardier leads. This order - the largest ever business aircraft sale in Bombardier's history - will help to sustain jobs and secure our long-term future, in addition to benefiting our local supply chain."
Bombardier in Belfast is responsible for the design and manufacture of a range of parts for the Global aircraft family, including the forward fuselages, engine nacelles, horizontal stabilisers and other components.
Work will start shortly and the first order involves 25 Global 5000, 25 Global 6000 and six Global 8000 jets, Bombardier said.
Steve Ridolfi, president, Bombardier Business Aircraft, said they were thrilled Vistajet had picked them.
"We welcome Vistajet's ongoing commitment to Global coverage within existing and developing new markets," he said. "Our Global aircraft are perfect for Vistajet's business strategy to deliver the ultimate business jet family to all corners of the world."
Unite union regional secretary Jimmy Kelly said: "This historic order is very welcome at this particularly fragile economic time. Unite understands that it will secure the current workforce levels for a number of years. It also shows that manufacturing in Northern Ireland is a world leader following the success at Wrightbus with its order for Transport for London."
Enterprise Minister Arlene Foster said the contract reflected confidence in the local workforce.
"Bombardier has had a presence in Belfast since 1989 and as our largest private sector employer they are pivotal to the local economy," she said. "This order, the largest ever business aircraft order in Bombardier's history, will help to sustain jobs and secure its long-term future, in addition to benefiting the local aerospace supply chain."