Purpose: Childhood immunizations have proven to be one of the most beneficial interventions to promote public health and prevent childhood deaths due to disease. However, global coverage of childhood immunization has decreased throughout the world due to guardians' growing hesitancy towards immunizations. This study aims to describe how specialist nurses promote legal guardians to adhere to national childhood immunization programmes. Design and Methods: This study had a qualitative design. Semistructured interviews with 11 specialist nurses, who were paediatric primary care nurses or nurse practitioners, were conducted. Data were analysed using qualitative content analysis. Results: The findings, with four main categories including four subcategories, showed nurses using both local guidelines and national guidelines to promote guardians to adhere to the childhood immunization programme. The main intervention the nurses did to promote childhood immunization coverage was giving legal guardians general information about the programme. With hesitant guardians, adopting a person-centred approach towards the legal guardian improved adherence. Practice Implications: Further research should focus on how specialist nurses can respond to guardians who decline immunization for their children, as this study identified difficulties in this area. Furthermore, research on guardians' perspectives towards childhood immunization may also help generate further effective guidance on how to promote immunization coverage among children. © 2024 The Author(s). Journal for Specialists in Pediatric Nursing published by Wiley Periodicals LLC.