The increasing role of Information and Communication Technology (ICT) in the banking sector has transformed financial operations, customer engagement, and risk management. This study examines the effect of ICT investments on bank performance in Nigeria, with a specific focus on Core Banking Systems (CBS), Digital Customer Relationship Management (DCRM), Big Data Analytics and Artificial Intelligence (BAAI), and Cyber security Systems (CSS). The study adopts Return on Investment (ROI) as the measure of bank performance and employs multiple regression analysis to assess the relationship between ICT investments and financial outcomes. Using secondary data from 13 Nigerian banks actively listed on the Nigerian Exchange Group (NGX) from 2013 to 2022, the study applies descriptive statistics, correlation analysis, and regression modeling to determine the significance of ICT components on ROI. The findings reveal that CBS (B = 0.402, t = 8.204, p = 0.000), DCRM (B = 0.511, t = 6.812, p = 0.000), and CSS (B = 0.228, t = 4.471, p = 0.001) and BAAI (B = 0.317, t = 4.731, p = 0.000) all have a positive but statistically significant effect on bank performance in Nigeria. It recommended that Nigerian banks increase investments in CBS and DCRM, develop structured AI adoption frameworks, and strengthen cyber security measures to enhance financial performance.