Mateusz Morawiecki said shopping malls would continue to have their operations limited, and cinemas, theatres and entertainment venues would remain closed until April 19.
Schools would stay shut, while international air and rail travel, suspended on March 15, would remain banned until April 26, Morawiecki told reporters.
The government-imposed restrictions were proving effective, he said, adding: "We are often being copied by others."
Poland’s borders would remain closed until May 3, Morawiecki said.
The government last week announced tough new restrictions on daily life, banning children under 18 from leaving home unless supervised by an adult, closing parks and beaches, and ordering most hotels to shut.
Officials have urged Poles to spend the upcoming Easter holidays at home and scrap any travel plans amid the COVID-19 epidemic.
Public gatherings of more than two people have been banned.
Health and government officials have urged Poles to stay home and practice social distancing.
The first infection was confirmed by Polish authorities on March 4, while the country's first coronavirus fatality was announced on March 12.
A total of 5,341 people have tested positive for the COVID-19 disease in Poland, with 164 deaths from the coronavirus so far, officials said on Thursday morning.