Previously, the longest flight was 15,349km and was run by Singapore Airlines.
While Cathay Pacific's Airbus A350-1000 would usually traverse both Arctic and Russian airspace, it is now avoiding Russia.
Many international airlines are avoiding overflying Russia due to the country's invasion of Ukraine.
"We are always running contingency routings for potential events or scenarios," an airline spokesperson told Bloomberg.
"The Transatlantic option relies on the facilitation of strong seasonal tailwinds at this time of the year in order for the flight time to be between 16 and 17 hours, thereby making it more favourable than the Transpacific route."
Currently, the carrier is asking permission to overfly alternative airspaces in order to resume the new route from JFK airport to Hong Kong.
Passengers may have to endure a long flight, but it comes with a silver lining; the new route will not include a stopover in LA, California, which was part of the previous route.
This is one of many new route announcements. Last week Air New Zealand announced the launch of one of the world's longest flights from Auckland to New York City. This will be the fourth-longest commercial flight.
Qantas' greatly anticipated Project Sunrise flights, which would fly direct from Sydney, London and New York, were postponed by the pandemic after initial trial flights. These are anticipated to take the top spots as the longest flights.
At 16,983km, the Sydney to London flight would be 1,500km longer than the world's current longest commercial route.