The Jan Karski Society announced the award for Ziegler in a statement on Thursday, Polish state news agency PAP reported.
The diplomat has been honoured for his determination in "building a Polish-German reality in a shared Europe," the charity said.
Ziegler has sought "to make Polish-German relations the best they can be," it added.
He will receive the Jan Karski Medal at a ceremony in the eastern Polish city of Lublin on December 9, officials said.
Ziegler worked at the German embassy in Warsaw in the 1990s, then helped prepare the EU's 2004 enlargement by Central and Eastern Europe countries, "assisting Poland's accession to the bloc," the Jan Karski Society said.
He currently works as deputy head of the Support Group for Ukraine in the European Commission, coordinating support for war-torn Ukraine and assisting Kyiv's bid to join the EU, the PAP news agency reported.
The Jan Karski Medal is named after Jan Karski, a Polish World War II underground courier who carried the first eyewitness accounts of the Holocaust to the world in the 1940s.
(pm/gs)
Source: PAP, Polish Radio