Norwegian has clocked up more than four million passengers flying on low-fares between Europe and the US since the first transatlantic service began in 2013.
The first low-cost, long-haul flights from Scandinavia to the US started in May 2013, followed by North Atlantic services from Gatwick in July 2014.
The airline started non-stop services between Paris and the US at the end of last year and is adding four new services from Barcelona in June.
US flights from the UK are being increased by 55% for this summer, in addition to 10 new routes with 38 new weekly transatlantic flights from Edinburgh, Belfast, Cork, Shannon and Dublin.
Norwegian chief executive, Bjørn Kjos, said: “Reaching this global milestone of flying four million passengers’ in under four years shows the huge demand for affordable travel across the Atlantic.
“Norwegian’s transatlantic offering is not only great news for the traveling public, but also for the local U.S and European economies, as we will bring more tourists that will increase spending, supporting thousands of local jobs.
“Our low cost long-haul flights to and from the US are only the beginning, as we have ambitious plans to continue offering passengers affordable high-quality transatlantic flights, to a range of other global destinations.”