Jet2.com and Jet2holidays have added more than 170,000 seats to winter-sun destinations such as the Canaries, Turkey, Cyprus, Greece and the Balearics.
The airline and package holiday operator said the extra flights were being added to services across its UK from October to March because of increased demand, rather than a response to slots being available after the collapse of Thomas Cook.
The additional seats include more than 65,000 from Manchester; almost 40,000 from Birmingham; more than 20,000 from Glasgow; and 15,000 seats from Newcastle.
There are also thousands of extra seats on sale from Belfast International, Edinburgh, East Midlands and Stansted.
Steve Heapy, chief executive of Jet2.com and Jet2holidays, said: “This week has seen an unprecedented amount of demand, and we have responded quickly to that by adding more flights and holidays to the sunshine this winter.
“This demand shows that holidaymakers want to get away, and with this extra capacity we are providing independent travel agents with even more choice and flexibility when it comes to offering customers our award-winning flights and Atol-protected package holidays.”
The extra capacity means there are now more than 100,000 additional seats on sale to the Canary Islands between October and March.
Almost 30,000 seats have been added to Turkey, with a major focus on October and the school holidays.