The prime minister was speaking at a press conference following a crisis management team meeting.
The schools will be closed down from Monday, but they will remain open for students until the end of this week to allow parents to make suitable arrangements, but no classes will be held from Thursday, the prime minister said.
"Today, we have 25 or probably 26 cases registered in Poland, but we want to do everything to slow down the spread of coronavirus," Morawiecki said.
The government also decided to close down all cultural institutions, including theatres, operas, museums and cinemas.
"From tomorrow, all those institutions will stop operating in the area that concerns gatherings of large numbers of people," said Culture Minister Piotr Glinski.
All creches and kindergartens will also be closed, Family and Labour Minister Marlena Malag said.
The shutdown means that 4.58 mln students from 24,000 schools and 1.41 mln children attending 22,000 kindergartens across Poland will stay at home. The decision affects both public and private facilities. (PAP)