The movement from traditional branch banking to mobile banking has caused banks to come up with strategies to attract more customers and retain existing ones. The desire to reduce both operational, administrative cost and competition has driven banks to adopt mobile banking. Technological advancements in the area of telecommunications and information technology have continued to revolutionize the banking industry. The Kenyan banking sector has witnessed many changes since the beginning of digital transformation. While the rapid development of information technology has made some banking tasks more efficient and cheaper, technological investments are taking a larger share of bank’s resources. There is a paucity of published work on the effect of mobile banking investment on financial profitability of Tier I commercial banks, particularly in the context of developing countries in the dynamic African region and specifically in Kenya. This study intended to bridge this gap in the knowledge that exists. The main objective of this study was to evaluate the effect of mobile banking investment on financial profitability in Tier 1 Commercial Banks in Kenya. The study employed a descriptive research design. The unit of study for the research was tier one banks in Kenya. The survey was administered to 190 participants as a representative sample of the entire population. The data for this study was collected using a self-administered questionnaire. Another type of data that was used is secondary data which will be derived from the previous studies and Tier I commercial banks’ financial statements. The quantitative data collected from respondents was analyzed using Statistical Package for Social Sciences (SPSS) to produce descriptive analysis and inferential statistics. Qualitative data obtained from the open-ended questions in the questionnaire was analyzed thematically. The study concluded that: Monthly value moved through mobile banking, and that the number of users of mobile banking do influence financial profitability of the banks to a very great extent. Therefore, this study concluded that there exists a positive association between perceived increased customer base, mitigating fraud and cybercrime, investing in security systems, and risk management practices that suggest that when one increases, financial profitability of the banks increase. The study recommends need for policy makers to consider mobile banking in their formulation of policies because of the technological developments and the expected switch from physical branch networks to technologically supported banking channels. There is also a need to conduct a study on the challenges faced in the adoption of mobile banking in commercial banks in Kenya.