MPs voted 266 to 190 to deny their backing to Morawiecki's new government on Monday afternoon, Polish state news agency reported.
Earlier in the day, the prime minister addressed parliament, outlining his policy plans.
MPs then held a debate on Morawiecki's new Cabinet, followed by a vote of confidence in the government.
Morawiecki, Poland's head of government since 2017, was reappointed prime minister by President Andrzej Duda in November, but his Law and Justice party lacks a majority in the new parliament.
Poland to have new PM on Monday night
The vote's result cleared the way for a broad-based coalition of pro-European Union opposition parties, led by Donald Tusk, to take power in Poland, the Reuters news agency reported.
Tusk's liberal Civic Coalition group is expected to form a coalition government with the centre-right Third Way alliance and the Left, after an election in October.
Tusk, a former top EU official, has pledged to repair Poland's relations with Brussels, unblocking billions of euros in grants and loans that had been withheld from Poland due to concerns over the rule of law, Reuters reported.
On Monday afternoon, MPs submitted Tusk's candidacy to be the new prime minister; a floor debate began at 5:30 p.m., and lawmakers were due to elect Tusk as new head of government in a vote at 8:15 p.m.
(pm/gs)
Source: PAP, Reuters