Human milk is recommended by the World Health Organization (WHO) for the general well-being of infants. However, many mothers face an insufficient milk supply to breastfeed their children. Galactagogue, in particular, plant galactagogue, serves as a method to promote lactation. This in-depth review examines the evidence supporting different plants’ galactagogic activity through clinical studies around the globe. A scoping review approach was adopted to establish the research questions, and define the findings, selection and analysis of the study. This scoping review highlights and compiles the clinical research performed globally involving plant galactagogue to better inform the medical practitioners, lactation consultants, nursing mothers, communities and relevant personnel on practicing, guidelines, policymaking and research. In general, a total of 1041 research publications were retrieved from different global bibliographic databases, of which only 13 articles were retained for analysis after applying the exclusion criteria. A total of 14 types of plants have undergone clinical studies in the past decade to verify their galactagogic activity. All but two showed a positive effect on promoting milk production. There were 42 articles categorised as excluded studies. The category includes review articles, surveys, case reports, introductory articles of regional plant galactagogue and preclinical studies, which involves animal testing and the studies exploring other issues related to plant galactagogue. The findings demonstrate that there is a significant research gap on the plant galactagogue using clinical studies. More clinical research is necessary to identify and verify the efficacy of various types of plant galactagogue for the benefit of humankind.