The food waste along the vegetable supply chain has become a major concern across the globe and measures are being sought to reduce its impact on food security, economy, environment and society. Soweto Market in Lusaka, Zambia, is among the biggest markets where food waste along the vegetable supply chain is extensive. However, there is a significant research gap, particularly on the causes of food waste along the vegetable supply chain at Soweto Market. To address this gap, this research aims to assess the factors causing food waste along the vegetable supply chain at Soweto Market. This research is envisioned to contribute to the existing body of knowledge on the reduction of food waste along the vegetable supply chain. The study adopted a deductive research approach and employed the descriptive research design. Empirical data were collected using survey questionnaires distributed to 110 smallholder farmers at Soweto Market who farm, package, transport, store and sell for themselves. Data analysis involved descriptive statistics, factor analysis and regression analysis using the Software Package for Social Sciences (SPSS). The study intended to establish the type of food waste and was restricted to understanding how factors such as market information, packaging, transportation, storage, processing linkage, quality and regulations as independent variables cause food waste along the vegetable supply chain The findings from descriptive statistics established that tomatoes, onions, carrots, okra and cabbages were among the types of food waste along the vegetable supply chain. It was also found that independent variables except for packaging showed high reliability and internal consistency. It revealed that processing linkage have a significant positive effect on food waste. These findings contribute to enhancing the reduction of food waste along the vegetable supply chain, which ultimately improves food sustainability. It is recommended that stakeholders in the vegetable supply chain use the insights from this study to review processing linkages along the vegetable supply chain at Soweto Market.