Commonly used in human geography, quality of life (QOL) refers to the way and degree to which objective human needs are met, not only existential ones, but also those regarding the development of the human personality. This article diagnoses QOL understood in this way in Poland and its changes between 2004 and 2018 (i.e. during modernization), which saw the continuation of systemic transformation after joining the EU. To fully identify the regularity of spatial differences in the analysed phenomenon, 380 local units are used as reference points. First, we formulated an operational definition of multifaceted QOL with its separate dimensions, as well as selecting and constructing organized indicators that can be determined at the local level. Then we quantified local differences in the rate of growth and the level of QOL using multivariate analysis. Third, on the basis of the obtained results, we sought to reach the most significant conclusions: (1) the dynamic economic growth, enjoyed in Poland in 2004–2018, did not change significantly the spatial diversity of the quality of life on a local level. (2) To a large extent, the persistent differences in the quality of life in Poland are related to the historical spatial differences in the level of urbanisation and the well-established, traditional economic structure of the specific territorial units. (3) A higher degree of urbanisation coupled with the service- and service and industry-related functional nature of the local units in Poland are conducive to a better quality of life. This confirms the regularities observed in the countries on the verge of a rapid economic development.