The use of microfinance in poverty alleviation and, by extension, as an instrument for sustainable social and economic development, represents a novel idea in sustainable finance. This study employed science mapping to examine 4049 Scopus-indexed documents explicitly concerned with microfinance. The goals of the review were to document the distribution of microfinance literature by type, volume, time, and geography, and to identify influential authors, articles, and a potential intellectual structure of this knowledge base. The first microfinance research was conducted in 1989, but the field attracted increased attention only after 2006, when the Nobel Peace Prize was awarded to microfinance pioneer Muhammad Yunus. This study does not find any single dominant school of thought in the field of microfinance, but rather identified three thematic research clusters: (1) a concentration on institutional aspects of microfinance, (2) scholars who used sophisticated research methods to evaluate the impact of microfinance, and (3) groundbreaking microfinance literature related to social justice more generally. As the first-ever, comprehensive bibliometric review of research on microfinance, this study provides benchmarks against which to assess the future evolution of this literature, a reference for scholars entering this domain, and targets for future development of this field of sustainability scholarship.