Effective vaccination communication with parents is critical in efforts to overcome barriers to childhood vaccination, tackle vaccine hesitancy and improve vaccination coverage. Health workers should be able to provide information to parents and other caregivers and support them in reaching decisions about vaccinating their children. Limited information exists regarding the perceptions of caregivers and health workers on the vaccination communication strategies employed in Nigeria. This study, which forms part of the 'Communicate to vaccinate' (COMMVAC) project, aims to explore the perceptions and experiences of caregivers and health workers in Nigeria on vaccination communication strategies implemented in their settings.We conducted the study in two States: Bauchi in Northern Nigeria and Cross River in the south. We carried out observations (n = 40), in-depth interviews (n = 14) and focus group discussions (FGDs) (n = 12) amongst 14 purposively selected health workers, two community leaders and 84 caregivers in the two states. We transcribed data verbatim and analysed the data using a framework analysis approach.Caregivers were informed about vaccination activities through three main sources: health facilities (during health education sessions conducted at antenatal or immunization clinics); media outlets; and announcements (in churches/mosques, communities and markets). Caregivers reported that the information received was very useful. Their preferred sources of information included phone text messages, town announcers, media and church/mosque announcements. Some caregivers perceived the clinic environment, long waiting times and health worker attitudes as barriers to receiving vaccination information.When delivering communication interventions, health workers described issues tied to poor communication skills; poor motivation; and attitudes of community members, including vaccine resistance.Communication about vaccination involves more than the message but is also influenced by the environment and the attitudes of the deliverer and receiver. It is pertinent for health policy makers and programme managers to understand these factors so as to effectively implement communication approaches.