Lublin topped a list of 66 cities rated in a report compiled by the Polish Robert Schuman Foundation and unveiled at a conference this week, according to the lublin.eu website.
"Lublin strives to achieve sustainable development on the social, economic and environmental levels," said Mayor Krzysztof Żuk.
He added that the ranking validated City Hall's efforts "to improve the quality of environment and life" for residents.
Lublin performs strongly domestically in terms of public health, public transport and air quality measures, according to City Hall.
The city is one of just three in Poland, alongside Gdynia and Tychy, that use electric trolleybuses to transport passengers, officials also said.
Earlier this year, Lublin beat international competition to be selected as European Youth Capital 2023.
The designation came after an international panel of judges decided that the Polish city would offer "the most interesting programme of activities in Europe with its unique energy" and ideas to inspire young people, according to local officials.