PurposeMotivated by a lack of evidence regarding the effect of migration on entrepreneurship in a highly informal country, such as Colombia, this paper has a twofold purpose. First, it explores how Venezuelan immigration affects entrepreneurial activity in Colombian regions. Second, it intends to shed light on this relationship, by distinguishing between formal and informal sectors.Design/methodology/approachWith a sample of 1,776,063 individuals, from the Labor Survey Gran Encuesta Integrada de Hogares (GEIH) from the Departamento Administrativo Nacional de Estadística (DANE), the authors employ an instrumental variable approach to account for the selection of immigrants into locations with more or less desirable conditions.FindingsThe results suggest Venezuelan immigration positively influences self-employment and own-account workers, but negatively affects employers. However, once these immigrants proliferate in the informal sector, the effects increase.Originality/valueThis paper brings new insights into the intersection between immigration, unofficial economies, and entrepreneurship. First, while the prior literature focuses on migration from developing to developed countries, migratory flows between developing economies and its effects on local entrepreneurial activity remain unexplored. Second, although informality is mostly common in developing countries, little (albeit growing) evidence of its role in the relationship between migration and entrepreneurship research exists. Finally, the authors bring together these two phenomena to enhance our understanding of different types of entrepreneurial activities when immigration and informality take place. Policy implications are derived from these insights.