Background: Refugees, asylum seekers and undocumented migrants are at risk of sexual and gender-based violence (SGBV) and subsequent ill-health in Europe; yet, European minimum reception standards do not address SGBV. Hence, this paper explores the nature of SGBV occurring in this sector and discusses determinants for 'Desirable Prevention'. Methods: Applying community-based participatory research, we conducted an SGBV knowledge, attitude and practice survey with residents and professionals in eight European countries. We conducted logistic regression using mixed models to analyse the data in R. Results: Of the 562 respondents, 58.3% reported cases of direct (23.3%) or peer (76.6%) victimization. Our results indicate that when men were involved, it most likely concerned sexual perpetration (adjusted odds ratio [aOR]: 4.09, confidence interval [CI]: 1.2; 13.89) and physical victimization (aOR: 2.57, CI: 1.65; 4), compared with females, who then rather perpetrated emotional violence (aOR: 1.85, CI: 1.08; 3.13) and underwent sexual victimization (aOR: 7.14, CI: 3.33; 16.67). Compared with others, asylum seekers appeared more likely to perpetrate physical (aOR 7.14, CI: 4; 12.5) and endure socio-economic violence (aOR: 10, CI: 1.37; 100), whereas professionals rather bore emotional (aOR: 2.01, CI: 0.98; 4.12) and perpetrated socio-economic violence (aOR: 25.91, CI: 13.41; 50.07). When group perpetration (aOR: 2.13, CI: 1.27; 3.58) or victimization (aOR: 1.84, CI: 1.1; 3.06) occurred, it most likely concerned socio-economic violence. Conclusion: Within the European asylum reception sector, residents and professionals of both sexes experience SGBV victimization and perpetration. Given the lack of prevention policies, our findings call for urgent Desirable Prevention programmes addressing determinants socio-ecologically.