Biological nitrogen fixation (BNF) is vital for enhancing soil fertility, particularly in smallholder farming areas with limited access to synthetic fertilizers. Despite this fact, the adoption of BNF is still very low. This chapter sought to explore the role of BNF in improving soil fertility among smallholder farmers and its adoption. We argue that the current understanding is devoid of the farmers’ practices for enhancing BNF, and that both field and controlled experiments may inflate the performance of BNF by negating farmer typologies and practices. In addition, current literature is focused on the economic returns from BNF and maintaining soil fertility, and this is limited in driving the sustainability of BNF. There is also limited knowledge of factors, values, and logics—like generational wealth, heritage, and care for the environment—which can spiral and/or curtail the adoption of BNF practices. We base our arguments on a review of 85 peer-reviewed journal articles from four bibliographic databases—Scopus, Web of Science, JSTOR, and Science Direct; gray literature from Zimbabwe’s primary public extension agency, AGRITEX; and limited interviews with smallholder farmers. The journal articles were analyzed for trends and themes using NVIVO. The analysis showed yield, soil health, and autonomy benefits for smallholder farmers when using BNF. However, the reported benefits may be comparatively inflated because most of the research work uses the worst farmer practice of monocropping with no fertilizer as the control. Yet, there are other farmer practices to which BNF can be compared. We propose a rethinking of BNF not as a purely field-localized practice but as a cycle mediated by farmers’ practices and experimentation with leguminous residues, animal manure, and everything in between for better integration of BNF into smallholder farming systems—dryland and irrigated—for sustainable and equitable soil fertility management.