IntroductionDespite abundant evidence showing immunization as a lifesaving public health measure, a large proportion of Nigerian children are still not or fully vaccinated. Lack of awareness and distrust of the immunization process by caregivers are some of the reasons for poor immunization coverage which need to be addressed. This study aimed at improving vaccination demand, acceptance and uptake in Bayelsa and Rivers State, both in the Niger Delta Region (NDR) of Nigeria through a human-centered process of trust building, education and social support.MethodsA quasi-experimental intervention christened Community Theater for Immunization (CT4I) was deployed in 18 selected communities between November 2019 and May 2021 in the two states. In the intervention localities, relevant stakeholders including the leadership of the health system, community leaders, health workers and community members were engaged and actively involved in the design and performance of the theaters. The content for the theater showcased real stories, using a human-centered design (HCD) of ideation, co-creation, rapid prototyping, feedback collection and iteration. Pre- and post-intervention data on the demand and utilization of vaccination services were collected using a mixed method.ResultsIn the two states, 56 immunization managers and 59 traditional and religious leaders were engaged. Four broad themes implicating user and provider factors emerged from the 18 focus group discussions as responsible for low immunization uptake in the communities. Of the 217 caregivers trained on routine immunization and theater performances, 72% demonstrated a knowledge increase at the post-test. A total of 29 performances attended by 2,258 women were staged with 84.2% of the attendees feeling satisfied. At the performances, 270 children received vaccine shots (23% were zero-dose). There was a 38% increase in the proportion of fully immunized children in the communities and 9% decline in the proportion of zero-dose children from baseline.ConclusionBoth demand- and supply-side factors were identified as responsible for poor vaccination in the intervention communities. Our intervention demonstrates that caregivers will demand immunization services if they are engaged through community theater using a human-centered design (HCD). We recommend a scaling up of HCD to address the challenge of vaccine hesitancy.Supplementary InformationThe online version contains supplementary material available at 10.1186/s12919-023-00263-0.