Background The need for donor human milk has accelerated both locally and globally. To remain sustainable, human milk banks need to maintain effective recruitment including frequent donations of adequate volumes. Research aims To determine (1) which factors influenced mothers’ willingness to give or receive donor human milk, and the influence of (2) socio-demographics, (3) pregnancy, (4) breastfeeding history, (5) prior knowledge of human milk banks, and (6) general factors on milk donations. Methods This was a cross-sectional, prospective, descriptive study. Interviewer administered questionnaires were used ( N = 148). Independent sample t-tests and one-sample t-tests were used to determining differences in variables. Results The sample population consisted of mainly single ( n = 104, 70.3%) Black African mothers ( n = 127, 85.8%) who identified as Christian ( n = 97, 65.6%) with a mean age of 24.8 ( SD = 5.63) years. The majority ( n = 120, 81.1%) had no prior knowledge of human milk banks; however, most ( n = 78, 52.7%) were significantly likely to donate. The main factors that influenced the participants’ willingness to donate were altruism ( n = 99, 66.9%), information provided by staff at hospitals/clinics ( n = 92, 62.2%), amount of milk produced ( n = 69, 46.4%), fear of not having enough milk for their own infant ( n = 68, 45.9%), and support from family/friends/partner ( n = 67, 45.3%). Conclusion There is a strong need to increase visibility and information sharing with potential donor mothers to ensure a sustainable supply and system of human milk banks.