Studies have explored social capital (SC) in diverse ways. Still, little is known in the literature about how its functional areas, including bonding, bridging and linking relationships, interact to facilitate sustainable development, particularly in agricultural diversification. We address this gap by using the rural web and the social capital frameworks to (1) analyse factors influencing SC and (2) assess the relationship between SC and agricultural diversification. Drawing on a survey of 600 rural households and 60 interviews with key stakeholders from the Upper West and Ashanti regions of Ghana, we found that socioeconomic factors, including farm size, remittance, household size and education, significantly influence bonding, bridging and linking SC. The findings also show that rural farmers depend strongly on bonding, bridging and linking SC to improve their livelihoods through agricultural diversification. These findings have implications for achieving SDG targets, particularly poverty reduction (SDG 1) and food security (SDG 2), regarding accessibility to resources, market participation, social empowerment, and contract farming. Therefore, agricultural policies in sub‐Saharan Africa should incorporate SC as a critical indicator for achieving agricultural diversification initiatives and sustainable development objectives.