Thomas Cook is to increase capacity for summer 2018 by 230,000 seats.
The company’s airline and tour operations capacity will rise by 115,000 seats at Luton and by the same number at Leeds Bradford.
Cook also said it was “finalising plans” for further growth at other UK airports.
It follows the collapse of Monarch last week, which had operations from both airports and had its head office in Luton.
Since then, both Jet2.com and Thomson have increased capacity at former Monarch bases.
From Luton, Thomas Cook will add 13 flights a week, to Palma, Dalaman, Antalya, Izmir, Bodrum, Larnaca, Corfu and Tunisia.
From Leeds Bradford, 12 more flights will go to Palma, Mahon, Tenerife, Larnaca, Dalaman, Antalya and Tunisia.
A spokeswoman for Thomas Cook said: “We have increased our airline and tour operations capacity by 115,000 at London Luton Airport and 115,000 at Leeds Bradford airport for Summer 2018 and we are finalising plans for further growth in other UK airports.”