Abstract Digital public health interventions (DHIs), like smartphone apps supporting weight loss, can deliver services at scale and low marginal cost, changing the way complex public health problems are tackled.Digital and Research, Translation and Innovation teams from Public Health England (PHE) are developing a practical, embedded approach for evaluating the effectiveness and value of DHIs. A multidisciplinary team composed of service designers, academics, and public health professionals was formed to deliver the work, following agile methodologies. The “discovery” and “alpha” phases were completed in July 2018 and March 2019 respectively. In discovery, research included in-depth interviews (n=15) with stakeholders (Directors of Public Health, clinical academics, career scientists) and users (public health analysts, service owners, product managers) alongside desk research and stakeholder workshops. In alpha, similar qualitative methods were used to co-design concepts and prototypes. Research was sense-checked by a working group of academics, public health and digital professionals from bodies including the National Institute of Health and Care Excellence and University College London.Initial research indicated users developing DHIs have unmet needs for evaluation support. Digital professionals, for example, need an evaluation framework that supports richer success metrics, rather than simple ‘vanity' metrics (clicks, views). The resulting alpha prototype focuses on unmet user needs, enabling teams delivering DHIs in the public sector to develop effective evaluation strategies.PHE will use this novel project to evaluate its own DHIs, and the approach will be shared with the wider public health system for other developers to use. External funding details Funded by PHE.