Startups operate in dynamic environments where rapid scaling determines success. This paper explores data science's role in startup growth, with case studies from Nigerian tech startups at innovation hubs like Co-Creation Hub (CcHub) and Ventures Platform. Using mixed methods, the study analyzes how data-driven strategies are used during key growth phases: ideation, product development, market entry, and scaling. Results show startups using data science tools such as predictive analytics, customer segmentation, and operational modeling make quicker, more accurate decisions, attract customers better, and grow revenues steadily. Early adoption of data science and internal analytics expertise led to better scalability. Incubators support this with mentorship, infrastructure, and a data-friendly culture. Challenges include limited technical talent, poor data governance, and misaligned tools, especially in sectors like agritech. The study concludes that data science is a strategic driver of scalable innovation, not just support, with recommendations for founders, incubators, and policymakers to build data skills, promote ethical analytics, and create supportive policies. Overall, the research highlights the transformative role of data science in African startup ecosystems.