Security services were verifying the reported threat in Modlin, the airport said in a statement on Tuesday.
"At 9.54am, a bomb threat alert was announced on board an aircraft operating a flight on the route London Heathrow (LHR) - Warsaw Chopin Airport (WAW). At 10.01am, a Boeing 737 MAX aircraft landed at Warsaw/Modlin Airport," it said.
The 181 people aboard the plane were being evacuated, it said.
Warsaw-Modlin Airport was closed before resuming operations.
"The aircraft which was the subject of a report of a possible bomb threat is currently being checked by the relevant services. Passengers and crew members remain in the arrivals hall to wait for further decisions," the airport said.
A spokesperson for Polish airlines LOT confirmed it was a LOT flight.
A bomb threat was also reported on an SAS flight from Copenhagen to Warsaw, which landed at Chopin Airport and was being checked, a Warsaw-Chopin airport spokesperson said, adding that the airport was continuing operations.
Warsaw has two airports - Chopin is within the city limits and Modlin, mostly used by budget airlines, is about 36km from the capital.
