Despite progress in maternal health services, rural Zambia continues to record high rates of home delivery. Birth Preparedness and Complication Readiness (BPCR) is promoted to reduce delays in accessing skilled birth care, yet limited qualitative evidence exists on how preparedness influences actual delivery-site decisions among postpartum women. This qualitative study explored the role of birth preparedness in delivery-site selection among breastfeeding women in Petauke and Lusangazi districts, Eastern Province, Zambia. A descriptive phenomenological design was employed involving semi-structured interviews with 17 breastfeeding women who delivered at health facilities and four focus group discussions with 20 women who delivered at home. Data were analyzed thematically following Braun and Clarke’s approach. Birth preparedness emerged as the strongest determinant of delivery-site choice. Women who delivered at health facilities reported deliberate preparation including saving money, arranging transport, attending antenatal care, and preparing delivery items. In contrast, home delivery was associated with financial constraints, long distances, lack of emergency transport, cultural restrictions, limited decision-making autonomy, and low perceived risk. Strengthening birth preparedness particularly financial planning, transport readiness, male involvement, and community health education has high potential to increase institutional deliveries and reduce preventable maternal and neonatal risks in rural Zambia.