This study investigates ethnic residential segregation in Catania, a key urban centre in Southern European regions, between 2011 and 2021. Utilizing entropy-based Theil’s H index, we explore segregation patterns at micro and macro spatial scales. The Urban-to-Extra-Urban (UEU) classification is employed, offering a comprehensive view of spatial segregation dynamics. Results reveal a dual trend: localized desegregation juxtaposed with broader spatial clustering, particularly for Bangladeshi and Mauritian populations. The decomposition of Theil’s H index highlights the reduction in micro-segregation across UEU zones, indicating localized integration, while macro-segregation trends emphasize clustering in central zones. Our findings on the residential interplay between native and migrant populations provide critical insights for targeted urban policies. By extending methodologies from U.S. urban studies to the European context, this research enhances our understanding of socio-spatial inequalities in Southern European urban areas and sets the stage for comparative analyses across diverse urban settings.