The twice-daily weekday service, and daily weekend service, from London City was revealed last June.
LOT will operate the route with four brand-new Embraer 190 jet aircraft.
The route builds on LOT’s recently launched London City-Warsaw service, and its operations at the Docklands airport will grow with the addition of a Vilnius route from May 1.
Flights to the Hungarian capital depart London City at 9.15am (excluding Sundays) arriving 12.45pm, and 7.30pm (excluding Saturdays) arriving 11pm.
