Kangaroo mother care (KMC) is an evidence-based method to improve newborn survival. However, scale-up even for stable newborns has been slow, with reported barriers to implementation. We examined facilitators and barriers to initiating KMC before stabilisation amongst neonates recruited to the OMWaNA study in Uganda. A qualitative sub-study was conducted during the OMWaNA randomized controlled trial examining the mortality effect of KMC prior to stabilisation amongst newborns (700-2000g). At the four trial site hospitals, focus group discussions (FGDs) were conducted with caregivers, and separately with healthcare providers and in-depth interviews (IDIs) with caregivers (admitted/recently discharged), and key informant interviews (KII) with hospital administrators/neonatal healthcare providers. The WHO Building Blocks was used to guide thematic analysis. Eight FGDs (4 caregivers, 4 healthcare workers), 41 caregiver IDIs (26 mothers, 8 grandmothers and 7 fathers) and 23 KIIs were conducted. Key themes based on the building blocks were family and community support and involvement, health workforce, medical supplies and commodities, infrastructure and design, financing, and health facility leadership. We found availability of an additional family member in the hospital, and support from healthcare workers, were facilitators for KMC before stability. The caregiver’s positive attitude towards KMC facilitated KMC practice but was impeded by the lack of knowledge on the benefits of KMC or how to perform it. Implementation barriers included: Fear of inadvertently causing harm to the newborn, inadequate space to perform KMC in the neonatal care unit and a limited number of trained healthcare workers coupled with insufficient medical supplies. In the Ugandan government hospital setting, the presence of a family member in the hospital, adequate provision of healthcare workers knowledgeable in supporting KMC prior to stability, and adequate space for KMC beds where neonatal care is being delivered, can enable implementation of KMC before stability.