Vaccination is known to be one of the most cost-effective ways to avert child deaths. However, in Nigeria, the vaccination completion rate among children is extremely low and the child mortality rate is one of the highest in the world. National immunization coverage survey shows that the low vaccination rate in Nigeria is partly attributed to service delivery issues. This paper evaluates the effect of Performance-Based Financing (PBF), an incentive scheme where health facilities are funded based on their performance, on the quantity of vaccinations carried out in Adamawa state. Under the Nigeria State Health Investment Project (NSHIP), half of the Local Government Areas (LGAs) in Adamawa State were randomly assigned to receive PBF intervention between 2015 and 2018. The Difference-in-Differences (DiD) technique as well as ANCOVA analysis are used to evaluate the effect of PBF on vaccination service delivery indicators. We find that the PBF intervention significantly increased the quantity of full vaccination cases as compared to the comparison group, although the effect size was small. On the other hand, if health facilities receive intensified PEI (Polio Eradication Initiative) concurrently, the effectiveness of PBF in increasing the number of full vaccination cases do not differ significantly from health facilities that are not under PBF. Rather than providing conditional financial incentives such as PBF to health facilities, simply providing unconditional financial and technical assistance to strengthen routine immunization programs might be sufficient to increase the quantity of vaccination service provision. The positive effect of PBF on vaccination provision was not sustainable, either. Future work should explore how we can strengthen the health system in a cost-effective and sustainable way.