The decision came just days after the Polish authorities introduced a series of restrictions urging citizens to stay at home and work remotely as far as possible.
The National Arena has conference rooms under the stands and it is these that the health service uses.
"Approximately 500 beds will be installed to receive infected people who require hospital care," said Piotr Müller, a spokesman for the Polish government.
50 of the beds are adapted for intensive care and should be able to be used from the end of this week.
If required, field hospitals will be built in each of Poland's 16 administrative regions.
About half of Poland has been designated a "red" zone since Saturday.