Severe acute malnutrition (SAM) in infants aged <6 months is a major global health problem. Supplementary suckling (SS) is widely recommended as an inpatient treatment technique for infant <6 months SAM. Its aim is to re-establish effective exclusive breastfeeding. Despite widespread support in guidelines, research suggests that field use of SS is limited in many settings. In this study, we aimed therefore to describe and understand the barriers and facilitating factors to SS as a treatment technique for infant SAM. We conducted qualitative interviews and focus group discussions in a hospital setting in Blantyre, Malawi, with ward staff and caregivers of infants <2 years. We created a conceptual framework based on five major themes identified from the data: (1) motivation; (2) breastfeeding views; (3) practicalities; (4) understanding; and (5) perceptions of hospital-based medicine. Within each major theme, more setting-specific subthemes can also be developed. Other health facilities considering SS roll-out could consider their own barriers and facilitators using our framework; this will facilitate the implementation of SS, improve staff confidence and therefore give SS a better chance of success. Used to shape and guide discussions and inform action plans for implementing SS, the framework has the potential to facilitate SS roll-out in settings other than Malawi, where this study was conducted. We hope that it will help pave the way to more widespread SS, more research into its use and effectiveness, and a stronger evidence-base on malnutrition in infants aged <6 months