Norwegian is making more than 13,000 seats on new transatlantic routes available from £99 one-way.
The special rates are available to book from today until 11.59pm on June 3.
The offer covers flights from Edinburgh between June 15 and March 2018 and from Belfast between July 1 and next March.
The 10-day deal is available on new routes to Stewart International airport in New York state and Providence airport for connections to Boston and New England.
The £99 fares also include as flights from Edinburgh to Bradley International airport in New England.
Passengers from Cork, Dublin and Shannon are being offered €99 one-way fares for travel between July and March 2018.
The low-cost carrier plans to run 14 transatlantic flights a week from Edinburgh starting on June 15 and five a week from Belfast from July 1.
Dublin will see 12 departures to the US a week and three a week from Cork starting on July 1 and four a week from Shannon from July 2.
Norwegian chief commercial officer Thomas Ramdahl said: “The countdown is now underway to Norwegian’s exciting new transatlantic routes, and passengers across Scotland, Ireland and Northern Ireland now have another chance to bag a bargain flight to the US.
“With more choice, never before seen routes and now a range of special fares on offer, there has never been a better time to plan an affordable American adventure.”