This study focuses on the post-socialist urban development that evolved in Gdańsk, Poland. It aims to evaluate the effects of an urban regeneration project implemented in Granary Island, a central historical district, on the city identity. To achieve this goal, the study measures citizens’ identification by comparing both the new urban regeneration project and the historical inner city. The study discusses the relationship between urban identity and urban transformation. The methodology includes visual documentation, mapping, and social surveys supported by statistical analysis methods. Aiming to have a city-scale social representation, the survey was conducted with respondents (N = 210) from seven selected neighbourhoods within the city, evaluating identification and exploring its factors, considering physical and non-physical aspects. The identification with historical inner city is higher when compared with the newly regenerated area of Granary Island, although in both cases, most residents replied positively. The main reasons for identification with historical inner city are reported as self-described pride due to its cultural heritage values and historical old built environment, whereas for Granary Island, usage of old architectural elements in modern built environment, qualitative new built environment, and atmosphere created by new activities, social life, and cultural diversity. The citizens of more distant neighbourhoods reported lower identification.