The civilian distinction was created by the European Parliament to recognise contributions to European integration and the defence of European values.
The awards were presented during the parliament's plenary session in Strasbourg.
Wałęsa, the former Solidarity trade union leader whose movement helped bring down communist rule in Poland, received the title of Distinguished Member of the European Order of Merit.
The same rank was awarded to former German Chancellor Angela Merkel and Ukrainian President Volodymyr Zelensky.
Buzek, who served as Poland's prime minister from 1997 to 2001 and later as president of the European Parliament, was named an Honourable Member of the order, a category that included 10 recipients.
The inaugural group of 20 laureates also included former Irish President Mary Robinson, Moldovan President Maia Sandu and members of the Irish rock band U2.
Another seven recipients were named Members of the European Order of Merit, including Ukrainian human rights lawyer Oleksandra Matviichuk, head of the Centre for Civil Liberties, which shared the 2022 Nobel Peace Prize.
Announcing the laureates earlier this year, European Parliament President Roberta Metsola said the award recognises people who helped shape Europe through civic courage and commitment.
"Europe has always been built by people—bridging divides, breaking barriers, overthrowing dictatorships and overcoming crises for a better future for our continent," Metsola said.
"With the European Order of Merit, we honour those who did not simply believe in Europe, but who helped build it," she added.
The selection committee included Metsola; European Parliament Vice Presidents Sophie Wilmès and Ewa Kopacz; former European Commissioner Michel Barnier; former European Commission President José Manuel Barroso; former EU foreign policy chief Josep Borrell; and former Italian Prime Minister Enrico Letta.
Candidates were nominated by heads of state and government, Speakers of national parliaments and leaders of European Union institutions.
The European Order of Merit was established to mark the 75th anniversary of the Schuman Declaration, the 1950 statement widely regarded as the foundation of the European integration project that later evolved into the European Union.
The award is intended to honour individuals who have made significant contributions to European unity and the promotion of the values enshrined in EU treaties.
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Source: IAR, PAP