Children under 16 are allowed to leave their homes only under the supervision of an adult between 8am and 4pm.
Meanwhile, pubs, restaurants and cafes are as of Saturday allowed only to provide take-aways and delivery orders.
Gatherings of more than five people have been forbidden, though people who live or work together are exempt from the rule.
Prime Minister Mateusz Morawiecki announced the new rules on Friday as COVID-19 cases soared.
The government has appealed to people aged over 70 not to leave their homes unless necessary.
Poland on Sunday reported 11,742 new coronavirus infections and 87 additional deaths, bringing its total number of cases to 253,688 and fatalities to 4,438.
Health Minister Adam Niedzielski warned at the end of last week that new infections in the country could surge to 25,000 a day if social distancing and other measures were not widely respected.
Source: Polish Radio/IAR/PAP