Early in 2021, India embarked on the uphill journey of the COVID-19 vaccination of the largest population group in the world in a prioritized manner and in the shortest possible time. Considering the endless variety of geography and diverse socio-economic demographic, religious, and community contexts, there was a high likelihood of certain population subgroups with known vulnerabilities facing inequities, which were anticipated to be further accentuated by a digital divide. This necessitated devising solutions for such communities in a localized manner to aid the local government in breaking the service access and uptake barriers with an inclusive approach. To bridge this vital gap, the Momentum Routine Immunization Transformation and Equity project implemented a three-tiered collaboration, viz., government, non-governmental organizations (NGOs), and a wide range of vulnerable and at-risk communities, utilizing knowledge exchange and use of data. The project implemented localization strategies through the NGOs for community engagement in conjunction with government vaccination teams to universalize COVID-19 vaccination uptake up to the last mile. The collaboration resulted in reaching close to 50 million beneficiaries through messaging and facilitated the administration of more than 14 million vaccine doses, including 6.1 million doses for vulnerable and marginalized communities in 18 States and Union territories in India, along with suggesting implications for public health practice and research.