This study explored the role of mobile applications in enhancing service marketing effectiveness within Nigeria’s financial services sector. The study aimed to evaluate how mobile apps contributed to service personalization, improved customer accessibility to financial services, enhanced customer engagement and satisfaction, and strengthened the competitiveness of financial institutions in Nigeria. Using a quantitative approach, data were collected from a sample of financial services customers and providers through surveys, focusing on mobile app features and their impact on service delivery. The findings revealed that mobile apps significantly enhanced service personalization, improved accessibility to financial services, and positively affected customer engagement and satisfaction. Furthermore, mobile apps were found to boost the competitiveness of financial institutions by driving customer retention and expanding market share. The study provided actionable recommendations for financial institutions to further optimize mobile app features to meet evolving customer needs and remain competitive in the digital financial services landscape. The results underscored the critical role of mobile applications in reshaping service marketing strategies and driving growth in Nigeria's financial sector.