Tusk's successor as prime minister Beata Szydlo, acting on orders from her party boss and long-time Tusk adversary Jaroslaw Kaczynski, had vowed to stop him securing a second 30-month term. But the other 27 leaders wasted no time in moving to a cold-blooded vote in which she was the lone objector.
Of the 28 EU nations, only Poland voted against Mr Tusk, according to a tweet by the Czech prime minister.
Ms Szydlo has accused her predecessor of interfering in domestic politics through his support for Poland's centrist opposition party.
Mr Tusk served as the country's PM from 2007 to 2014.
Warsaw portrayed the issue as one of fundamental principle, in which vital national interests had been ignored by a Brussels machine dominated by "German diktat". Its crushing defeat showed how far the biggest of the ex-communist states that joined the EU after the Cold War appears isolated, even in Eastern Europe.
The row, albeit driven by Polish domestic politics, clouded attempts at the meetings in Brussels on Thursday and Friday to forge a common front as Britain prepares to deliver its formal notice that it will exit the bloc in 2019.
Kaczynski said the vote showed the EU was run by Germany and was trampling on national interests: "If the EU does not abandon this road, it will be consigned to history," he said in Warsaw.
Hours after the vote, after leaders agreed common positions on the economy, trade, migration and other issues, Szydlo was refusing to sign off on the official record of "conclusions".
She said this rendered the summit invalid, but EU officials said Polish refusal to endorse the text would have no legal impact.
Szydlo had first tried to get the other leaders to postpone a decision on Tusk but found no backing. They gave her time to repeat her reasons for withholding her support, citing Tusk's criticism from Brussels of her government's policies - policies many in the EU see as a threat to democracy.
But Maltese Prime Minister Joseph Muscat, who holds the rotating EU chair, moved swiftly to record a 27-1 vote to reappoint the 59-year-old Tusk.
Tusk had left the room during the discussion and was clapped back in by all but Szydlo, according to people who were present. He will play a key role over the next two years in overseeing Brexit negotiations with London. Prime Minister Theresa May was attending her last summit before launching the process.
Tusk, who led a centrist government for seven years until 2014, offered an olive branch to Szydlo, telling the Council in broadcast comments that he would work with the leaders "without any exceptions - because I am committed to European unity".
He urged Warsaw to be "reasonable" and not "burn bridges" with EU allies and said he would work to avoid its "isolation".
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