Across six countries, 25 embedded research teams worked with immunization programmes to generate and apply evidence in real time. This led to measurable improvements in programme implementation at subnational level, including increased adherence to vaccination schedules in Ebolowa district, Cameroon (from 64% to 85%), reduced response times to zero-dose alerts in a union council in Lahore, Pakistan (from 10 days to 3), and improved acceptability of vaccine services in Toamasina I and Mahanoro districts, Madagascar (from 56% to 86%). Additional studies informed more targeted outreach through geospatial mapping in Malawi and identified missed opportunities for human papillomavirus (HPV) vaccination within routine service delivery.