This dissertation investigates the role of digital platforms as institutional intermediaries in emerging markets where underdeveloped institutional infrastructure limits access to resources and leaves individuals and businesses excluded from formal markets. In these settings, local institutional conditions may shape the roles and outcomes of digital platforms. This allows a closer examination of mechanisms that may be under-theorized or under-observed in more developed contexts. I study financial technology platforms in emerging economies and take the perspective of three key actors in platform ecosystems—end users, agents, and incumbent firms. Chapter 1 sets the stage by demonstrating the mechanisms through which digital platforms act as institutional intermediaries and fill institutional voids for end-users. Using cross-country data from 78 countries, it shows that mobile money platforms expand access to formal credit through mechanisms distinct from traditional intermediaries. Chapter 2 shows that this intermediation function of platforms is not frictionless. Given the persistent last-mile problem in emerging markets, relational considerations play a key role in platform strategy. Taking the lens of agents who serve as the face of the platform and connect platforms with customers at the last-mile, this chapter shows that while agents’ prior relationships with customers are foundational to firms scaling in these contexts, these relationships can constrain platform activity when a platform owner serving low-income, rural markets shifts from prioritizing scale to profitability. Chapter 3 turns to incumbent firms and examines if these firms potentially benefit from the purported democratization benefits of digital platforms and the heterogeneity in the same. Drawing on regulatory changes in the mobile money industry, this chapter shows correlational patterns indicating that smaller banks may experience gains, while the largest banks may experience declines from the advent of mobile money platforms. Crucially, these associations are contingent on bank-platform partnerships and their timing. Large banks see a positive association of the onset of mobile money platforms with their outcomes if they partner with platforms post-reform, while early partnerships may strengthen the correlation with gains for smaller banks. Taken together, the dissertation provides a contextually grounded, nuanced understanding of how digital platforms operate as institutional intermediaries and the mechanisms through which they produce heterogeneous outcomes for various actors in emerging markets.