PurposeThis study aims to investigate whether social capital mediates the impact of financial capital on business performance in Cameroon.Design/methodology/approachThe study uses quantitative data collected from 370 small businesses in Yaoundé and Douala in Cameroon. All businesses in the sample are formally registered and are in the services sector. A structural equation modelling (SEM) approach is used for the analysis.FindingsStructural and relational capital constraints are significant mediators of formal and informal finance. The magnitude effects of relational capital are the largest, underlining information's importance in resolving small and medium enterprises’ (SMEs') financial constraints. In addition, the effect of informal finance constraints on business performance is larger in magnitude, confirming the substantial impact of informal finance on SME operations.Research limitations/implicationsThe paper confirms that relational and structural social capital are vital in business. However, the study did not investigate the disaggregated effects of these dimensions of social capital. Furthermore, how SMEs transition between formal and informal finance could provide further understanding of the role of social capital. A disaggregated and panel data set would help to provide additional insights.Practical implicationsSocial capital emerges as a pivotal factor in enhancing SME access to finance. The results, therefore, confirm the relevance of a holistic approach to easing financial capital constraints for SMEs and enabling small businesses to connect more to various stakeholders to amplify business performance. In addition, the findings identified some intervention points for the governments in Cameroon as it seeks to use SMEs as its pivot for development and to catapult itself to emerging economy status in its Cameroon 2035 vision.Originality/valueThe value of the study lies in assessing the mediating effect of cognitive, relational and structural social capital constraints on business performance and comparing the effect of formal and informal financial constraints on business performance.