The new measures, to remain in force at least until April 11, mean that Poles can leave their homes only for essential purposes, including travel to work or to the doctor's, shopping for essential items or walking their dog, PM Mateusz Morawiecki and Health Minister Lukasz Szumowski announced at a press conference on Tuesday.
People will be allowed to go out to help the elderly and family members.
Poles are now completely banned from gathering or moving in groups of three or more, unless they are members of a single household.
Religious gatherings of up to five people are still possible, the health minister said.
"If we don't limit these contacts as much as possible, we won't limit the number of the ill and we won't save people's lives," Szumowski said.
On public transport, there can only be one passenger per two seats, PM Morawiecki said. "But first of all, let's leave public transport for people who have to go to their workplaces," he added.
Those who break the rules will face a fine of PLN 5,000 (EUR 1,085) the health minister warned.
The army and territorial defence forces have been asked to help enforce the restrictions, PM Morawiecki announced.
The new restrictions also limit the operation of courts and state administration, with only larger rooms being allowed for use when a few employees have to work together.
To limit travel, Morawiecki appealed to companies to make further efforts to facilitate work from home whenever possible.
The health minister said there were no plans to cordon off certain cities or suspend the operation of public transport.
The Polish government has already closed down schools, museums, libraries, entertainment facilities, restaurants and bars, and limited the operation of shopping centres.
As of Tuesday evening, the number of confirmed coronavirus cases in Poland reached 901. On Monday evening the figure was 749. Ten people have died from the virus so far. (PAP)