Contemporary reasons for migration are diverse and they are treated as the most active factor of human activity. Highlighting the scale of migration processes that generate challenges and threats in the modern world seems fully justified. Analysis of the experience of the influx of Ukrainian immigrants for economic purposes as a result of the migration crisis of 2015–2018, the mass influx of foreigners during the crisis on the Polish-Belarusian border and the specific exodus of war refugees from Ukraine as a result of the military conflict triggered profound changes in Poland’s migration policy. This article presents the expansion of the causes and effects of the above phenomena on state security in the social and economic dimensions. The role of migration policy in the new and changing security architecture was also highlighted.