The formation of formal markets in emerging economies is often constrained by complex, overlapping institutional logics. Understanding how entrepreneurial actors navigate this complexity is critical for analysing economic development. This study aims to elucidate the mechanisms of entrepreneurial agency within Kenya's institutional complexity, examining how entrepreneurs' strategic actions contribute to the co-construction of new market structures. A longitudinal, immersive ethnography was conducted, combining participant observation, in-depth interviews, and document analysis within Nairobi's entrepreneurial ecosystem. Data were analysed using an abductive approach, iterating between theory and empirical material. Entrepreneurs consistently engaged in 'institutional bricolage', blending formal regulatory, informal social, and transnational investor logics to create viable ventures. A dominant theme was the strategic performance of 'global readiness' for external capital, while simultaneously relying on deeply embedded social networks for operational resilience. Approximately two-thirds of observed ventures hybridised mobile money platforms with traditional trust-based credit systems. Market formation is an agentic, culturally embedded process wherein entrepreneurs actively negotiate and reshape institutional prescriptions, leading to hybrid market structures that defy neat categorisation as formal or informal. Policymakers should design regulatory frameworks that recognise and accommodate institutional hybridity. Investor due diligence should incorporate an understanding of entrepreneurial bricolage as a core competency, not a deviation. institutional complexity, entrepreneurial agency, market formation, bricolage, Kenya, ethnography This paper provides a novel, empirically grounded framework of 'institutional bricolage' as the core mechanism driving market formation in complex institutional environments, moving beyond descriptive accounts of constraints.