Wizz Air will add two aircraft at London Luton after acquiring a number of take-off and landing slots from Monarch.
It means it will have a total of seven aircraft at the airport, increasing capacity by 18% to 7.1 million seats in 2018.
Additional London Luton routes will be announced in due course, said the airline.
CEO Joozsef Vaaradi said: "We continue to develop our business in the UK. Following the announcements of establishing Wizz Air UK and our accelerated growth plan, just a few days ago here we go again.
"Acquiring airport slots and airport nightstands at Luton Airport will enable us to enhance our presence and competitive position in the London market.
"In summer Wizz Air UK will operate a fleet of 7 A320/A321 aircraft, to grow the overall Wizz capacity by 18% in 2018.
"While Brexit will certainly pose challenges to the airline industry, we see it as an opportunity for Wizz Air, as our highly efficient low fare model will prevail even more under the new circumstances."
