The discovery and understanding of Vitamin B12’s complex chemical structure mark significant scientific achievements that spanned over a century. Pioneering researchers such as Mary Shaw Shorb, Karl Folkers, Alexander R. Todd, and Dorothy Hodgkin collaborated and innovated across disciplines, leading to groundbreaking work in isolating Vitamin B12 and determining its molecular composition. This series of discoveries has had far-reaching impacts on medical research, nutritional science, and chemistry, laying essential groundwork for various applications including the development of supplements and understanding the vitamin’s role in human health.