LOT Polish Airlines will fly from London City Airport (LCY) to Warsaw up to twice a day from January 2019.
The airline plans to acquire four brand-new Embraer 190 jets for the route.
Adrian Kubicki, director corporate communications of LOT Polish Airlines, said: "We are extremely happy to announce this prestigious destination as our 100th connection in our network.
"LOT has a long lasting history of operations to London Heathrow, where we are flying three times a day. Now we are opening the new chapter by putting two daily flights to London City."
Richard Hill, chief commercial officer at London City Airport, said: "LOT’s arrival is a huge gain for London City Airport and its passengers, offering a gateway for trade and tourism in Central Europe.
"It demonstrates the airport’s commitment to attracting new routes, greater choice and more airlines ahead of our £480 million development.
"It also demonstrates that, despite Brexit, London remains open for business and connections between Poland will continue to be vital for each country’s economy."
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