The carrier says it is ending the route due to poor financial performance
The only trans-Atlantic service from Northern Ireland is to be scrapped in January.
It comes after the European Commission voted to block a stg£9m Stormont funding package to preserve the route.
United Airlines flew from Belfast International Airport to New York's Newark Airport.
The carrier said Friday it would end the daily service "because of the route's poor financial performance".
Several Democratic Unionist Party politicians have expressed disappointment.
Paul Girvan said: "We have been supportive of the retention of airline routes and direct routes to Northern Ireland and it is hugely disappointing that this decision has been handed down.
"This is a clear example of EU dictating what we can and cannot do. These unelected bureaucrats do not have the best interests of Northern Ireland at heart.
"It is a decision that is damaging to our economy, however it must be made clear that any public money has been recouped."
While Trevor Clarke added: "This news is very disappointing given the huge business and economic opportunities that were available to Northern Ireland as a result of having this direct route in place.
"Connectivity is so important to our economy and I know the Economy Minister will be doing everything to improve air connectivity here."