Objectives: The aim of this qualitative research study was to explore the barriers encountered by Ukrainian war migrants and refugees in accessing vaccinations in Poland and the challenges related to delivering vaccinations observed by healthcare professionals (HCPs). Material and Methods: The study was based on an analysis of data from 18 in-depth interviews with HCPs working with Ukrainian refugees conducted in Poland in July and August 2023. The authors analyzed the data using the UNICEF Journey to Health and Immunization (JHI) framework in order to identify bottlenecks and possible interventions that could solve existing problems in preventive healthcare for migrants. Results: This qualitative study revealed that at each stage of the JHI, there were challenges related to vaccinating Ukrainian children in Poland, which were similar to those experienced in other countries – gaps in routine immunizations and the need to fill these gaps by ensuring refugee populations are fully included in routine immunization in the host country. The work environment, training, and communication with the Ukrainian mothers contribute to HCPs’ engagement in increasing vaccine uptake among their patients. The HCPs’ attitudes, skills, and experiences impacted their interactions with patients and participation in the immunization process. Healthcare professionals observed that the mother’s journey was influenced by vaccine literacy level, competing priorities, individual barriers of access (e.g., language barrier, costs), as well as feelings associated with the decision to vaccinate a child, including worries about vaccine safety. The surrounding cultural norms, social support, and past experiences with the Ukrainian health system also influenced decisions on vaccinations. Conclusions: Overcoming barriers related to vaccinations requires a comprehensive approach, starting with expanding HCPs’ knowledge about migrants’ rights to health services, including vaccinations, improving communication between patients and HCPs, building vaccine literacy/trust in vaccinations, and achieving vaccination coverage through tailored and flexible systemic solutions. Int J Occup Med Environ Health. 2024;37(6):602–16