Internal control is a censorious component of bank management and bedrock for the safe and sound operation of deposit money banks and it helps them to achieve long-term profitability targets and maintain reliable financial and managerial reporting. Despite the implementation of internal control measures in Nigerian banks, lack of proper evaluation mechanism of procedures and policies has led to increased fraud in banks. Hence, the study examine the effect of internal control system on fraud prevention among deposit money banks in Kwara state Nigeria. Specifically, the study examine the effect of internal control components on fraud prevention of deposit money banks and the impact of internal auditors ‘involvements in risk management. The target population covered the whole deposit money banks in Kwara state. The study targeted all the 17 quoted banks in Nigeria located in Kwara state and purposive random sampling was used defined the sample frame as the researcher aimed to use one respondents in senior management, middle level management or members of the internal control departments in each bank. The study employed primary data obtained through well-structured questionnaire given to the personnel in senior and middle level management as well as the internal audit department. Descriptive statistics and ordered logit regression was used to achieve the objectives of the study. The study revealed that, there is a significant relationship between internal control system and fraud prevention of deposit money banks in Nigeria with p-value of 0.0023 at 1%, 5% and 10% level of significance. The study therefore concludes that internal control components and risk management improve fraud prevention in Nigeria deposit money banks. The study recommends that deposit money banks should put in place stronger control measures through more frequent meetings among the members of the risk management committee and also finance and investment committee.