BACKGROUND: General practices in England have continued to care for patients throughout the COVID-19 pandemic by instigating major changes to service delivery. Immunisations have continued, although the number of vaccines delivered initially dropped in April 2020. AIM: To evaluate how COVID-19 impacted the delivery of immunisations in London and identify innovative practices to inform future delivery, including for COVID-19 vaccines. DESIGN & SETTING: A mixed-methods study of immunisation delivery in London, UK. METHOD: An online survey of London general practices was undertaken in May 2020 to produce a descriptive analysis of childhood immunisation delivery and identify innovative delivery models. Semi-structured interviews were conducted between August and November 2020 to explore innovative immunisation models, which were analysed thematically. RESULTS: Sixty-eight per cent (n = 830) of London practices completed the survey and 97% reported having continued childhood immunisation delivery. Common delivery adaptations included spaced-out appointments, calling parents beforehand, and having only one parent attend. Forty-three practices were identified as having innovative models, such as delivering immunisations outside practice buildings or offering drive-through services. The thematic analysis of 14 semi-structured interviews found that, alongside adaptations to immunisation delivery within practices, existing local networks collaborated to establish new immunisation delivery models. Local population characteristics affected delivery and provide insights for large-scale vaccine deployment. CONCLUSION: Immunisations continued during 2020 with practices adapting existing services. New delivery models were developed by building on existing local knowledge, experiences, and networks. Immunisation delivery during the pandemic, including for COVID-19 vaccines, should be tailored to local population needs by building on primary care immunisation expertise.