Small businesses are vital to livelihoods in Zambia's informal economy but face significant threats to their sustainability. This study explores the vulnerability and prospects of small businesses at Kalikiliki Market in Lusaka. Guided by the Resource Dependence Theory, it employs a qualitative case study design to identify vulnerability factors, describe their impacts, and analyze their implications for the future. Data were collected through semi-structured interviews and observation. Ten business owners were purposively sampled, with their data analyzed thematically. The study revealed that vulnerability stems from external factors, including climate change-induced power shortages, unreliable electricity/fuel supply, limited access to clean water, economic uncertainties, and unfamiliar legislation. These factors force businesses to adopt coping strategies such as redirecting business objectives, diversification, downsizing, and, in severe cases, closure. The findings indicate that compared to larger enterprises, small businesses at Kalikiliki Market are at a higher risk of extinction due to their limited adaptive capacity. The study concludes that the future of these businesses remains uncertain, contingent on the stability of the external environment. It recommends targeted support from relevant ministries, focusing on business skills training and improving access to essential resources to enhance resilience. This research provides an in-depth, context-specific understanding of small business vulnerability in an urban informal settlement.