This study, grounded in Market Orientation Theory, examines the impact of entrepreneurship capacity building on the business success of street food vendors in the Arusha Region of Tanzania. Market Orientation Theory emphasizes the importance of understanding and responding to customer needs as a pathway to business success, a principle central to this research. Employing a descriptive cross-sectional design, data were collected from 150 registered street food vendors using structured questionnaires measuring financial management skills, marketing skills, innovation capacity, and business performance. The analysis revealed significant positive relationships between entrepreneurship training and business success, with financial management skills identified as the strongest predictor, followed by marketing and innovation capacities. The findings suggest that enhancing these market-oriented competencies enables street food vendors to better meet customer demands, adapt to changing market conditions, and improve overall competitiveness and sustainability. This study underscores the need for tailored capacity-building programs that address the unique challenges faced by informal sector entrepreneurs, offering valuable insights for policymakers, training providers, and development partners seeking to promote inclusive economic growth and poverty reduction in Tanzania’s urban informal economy.