Supermarkets and most other retailers closed for the first time on Sunday since liberal shopping laws were introduced in the 1990s after communism's collapse.
The change has stirred up a range of emotions in a country where many feel workers are exploited under the liberal regulations of the past years and want them to have a day of rest.
The law was proposed by a leading trade union, Solidarity, which said employees deserved Sundays off.
It found the support of the conservative and pro-Catholic ruling party, Law and Justice, whose MPs passed the legislation.
The Catholic church is influential in Poland as more than 90 per cent of Poles belong to the church.
Among the Poles who saw it as a good step toward returning a frazzled and overworked society to a more traditional lifestyle was 76-year-old Barbara Olszewska, who did some last-minute shopping Saturday evening in Warsaw.
"A family should be together on Sundays," Olszewska said after buying some food at a local Biedronka, a large discount supermarket chain.
The new law at first bans trading two Sundays per month, but steps it up to three Sundays in 2019 and finally all Sundays in 2020, except for seven exceptions before the Easter and Christmas holidays.
However, many Poles experience consumer freedom as one of the most tangible benefits of the free market era and resent the new limit.
Pro-business opposition parties warn that it will lead to a loss of jobs, and in particular hurt students who only have time to work at the weekends.
Even the All-Poland Alliance of Trade Unions opposed it, arguing that it would just push employees to work longer hours on Fridays and Saturdays and that the work would be harder because there would be more customers.
Another last-minute shopper on Saturday evening, Daniel Wycech, 26, saw more drawbacks than benefits.
"I am angry because this law wasn't prepared properly. It would have been much better to force store employers to make two Sundays per month free for each worker," Wycech said.
There are some exceptions to the ban, like petrol stations, pharmacies and shops at airports and train stations.
Anyone infringing the new rules faces a fine of up to 100,000 zlotys (£21,000), while repeat offenders may face a prison sentence.
In Hungary, another ex-communist country, a ban on Sunday trading imposed in 2015 was so unpopular that authorities repealed it the next year.
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