Norwegian saw passenger numbers rise by 10% in August to more than 3.6 million.
High demand for low-cost long-haul flights helped boost the carrier’s performance over the same month last year.
The airline achieved a 94% load factor on long-haul services flown by Boeing 787 Dreamliners and 89.6% across the rest of the network.
This was achieved despite capacity growing by a third year-on-year.
Norwegian will take delivery of 11 Boeing 787-9 Dreamliners,12 Boeing 737 MAX 8s and two Boeing 737-800s this year .
Chief executive Bjorn Kjos said: “We are very pleased that an increasing number of passengers choose Norwegian for their travels.
“I’d particularly like to point out our long-haul routes where the demand is high and continues to increase, not least between London and the US and Paris and the US.
“We also see that more passengers from other continents connect to other destinations in Norwegian’s route network, which underlines the importance of a strong and seamless operation across the airline.”
He added: “I am also pleased to see that despite a high increase in available seats, we are filling the planes.
“Our capacity growth is still high, but in line with our strategy, the growth will slow down compared to previous months.
“We have been through a long period of strong growth and going forward we will reap what we have sown for the benefit of our customers, staff and shareholders.”
Meanwhile, easyJet saw August carryings rise by 5.6% to almost 8.7 million passengers with an almost static load factor of 96.4%.
This gave the UK budget carrier a rolling annual total of 84.1 million passengers, up 5.8%.