MPs chose Tusk as the country's new head of government in a 248-201 vote on Monday night, Polish state news agency PAP reported.
It spelt the end for the eight years of rule by the right-wing Law and Justice (PiS) party.
After the MPs' vote on Monday, Tusk thanked "millions of Poles" for backing pro-EU opposition parties in the October election, helping effect a "historic change" in the country.
Earlier on Monday, Poland's conservative Prime Minister Mateusz Morawiecki failed to win a vote of confidence from lawmakers, opening the way for a coalition of pro-European opposition parties led by Tusk to take power.
Tusk's return as prime minister sets the stage for a thawing of Poland's relations with the European Union, the Reuters news agency reported.
The new head of government has vowed to unblock billions of euros in grants and loans from the EU, frozen due to Warsaw's dispute with Brussels over democratic standards.
Tusk is expected to give a speech to lawmakers on Tuesday laying out his government's plans, followed by a parliamentary vote of confidence.
Tusk's Cabinet is then expected to be sworn in by President Andrzej Duda at 9 a.m. on Wednesday.
Tusk last Friday unveiled the lineup of his future Cabinet and urged the head of state to appoint his government on December 13, in time for a crucial EU summit starting in Brussels the next day.
He said the summit would make decisions "of great importance to Poland's interests."
EU leaders are expected to discuss the war in Ukraine and a protest by Polish haulers at the border with Ukraine, among other topics, according to officials.
Tusk was Poland's prime minister from 2007 to 2014 before becoming president of the European Council, a role he held until 2019.
(pm/gs)
Source: PAP, Reuters