Developing an effective entrepreneurial ecosystem is viewed as a regional economic development approach that focuses on developing supportive circumstances that encourage the startup’s success. This study aims to investigate the impact of the entrepreneurial ecosystem on startups’ success and the variables that could play a mediating role in the relationship between entrepreneurial ecosystem and startups’ success. The research is based on face-to-face and online semi-structured interviews (the interview guide consisted of 9 open-ended questions) from second quarter of 2023 until the end of the third quarter of 2023 (the data collection phase was closed after meeting the criteria of data saturation). The participants were selected via purposeful sampling technique (20 owners or managers of startup companies including IT, customer service, food, transportation, etc. in Egypt). Thematic and content analysis is done by using NVivo software. From the analysis of the interviews, four themes are developed, and each theme consists of several codes. The first theme is the entrepreneurial ecosystem, with codes: competence development, education and training, enterprising culture and leadership, financial support, government policies and regulations, market openness, and intermediary services. The second theme is entrepreneurial characteristics, with codes: self-efficacy, entrepreneurial attitude, entrepreneurial intention, and entrepreneurial innovation. The third theme is entrepreneurial challenges, with codes: fierce competition, failure to plan and unrealistic expectations, knowledge and skills gaps, and ineffective marketing. The fourth theme is startup success, with codes: productivity, financial performance, and competitive advantage. This study found, that some elements are unimportant for startup’s ecosystem: government programs and support, commercial and professional infrastructure for entrepreneurs, and access to physical infrastructure for entrepreneurship. At the same time, the study confirmed that education and training, enterprising culture and leadership, financial support, government policies and regulations, and market openness are unimportant for startup’s ecosystem. Moreover, it is found that such elements as competence development and intermediate services should be additionally included in the ecosystem. From this study, the model that investigates the relationship between the entrepreneurial ecosystem and startup success was developed. Finally, some recommendations provided to decision-makers and current and future research.