The study aimed to determine the impact of recent immigration law reforms on crime dynamics among irregular migrants in Ukraine, Poland, Germany, and Italy. A mixed-method design combining legal and comparative analysis with content analysis of 15 legislative acts and 10 official reports was applied, allowing both regulatory and empirical evaluation. The findings revealed that document forgery (up to 38% in Ukraine), theft (up to 29% in Germany), and violent acts in detention facilities (up to 22% in Italy) remain predominant offence categories. Following reforms between 2021 and 2024, the number of registered criminal proceedings rose by 16% in Poland and 11% in Germany, reflecting intensified law-enforcement activity rather than a genuine increase in crime. In contrast, Italy showed an approximate to 9% decline in migration-related offences due to administrative reclassification. The study identified no direct causal link between the level of criminalization and actual crime incidence; instead, it highlighted the impact of reporting and classification practices on statistical growth. Countries with stable judicial control (Germany and Poland) demonstrated higher recording accuracy and greater legal consistency, with completion rates ranging from 53% to 84%.Overall, the results emphasize that harmonization of procedural safeguards and proportional enforcement remains crucial for achieving both deterrence and human-rights compliance in migration governance.