Donald Tusk made the announcement at a news conference on Monday, public broadcaster Polish Radio's IAR news agency reported.
The prime minister told reporters he had "decided to call local elections on April 7 and 21."
He added that "hopefully April will be a good month for Polish local governance."
According to Poland's electoral code, the next local elections have to be held between March 31 and April 23.
Earlier in the day, Tusk was hosted by President Andrzej Duda in the presidential palace.
Poland's leaders discussed foreign policy, including support for Ukraine and appointments to top posts in the European Union, according to officials.
The president said he and the prime minister would work together to "make sure that a politician from Poland takes up at least one of these posts."
Duda told reporters he had also called on the head of government to order the release of two MPs and former ministers with the Law and Justice (PiS) party, Mariusz Kamiński and Maciej Wąsik, who were jailed last week to serve a two-year sentence for abuse of power while in government, polskieradio24.pl website reported.
Source: IAR, polskieradio24.pl, rp.pl