National Audit Department (NAD) had repetitively recommended Federal Ministries/ Departments and Government-Linked Companies (GLCs) through its Auditor-General’s Report on the need to have an effective internal audit function to identify and mitigate weaknesses in their activities. Therefore, the purpose of this study is to examine factors that influence the effectiveness of the internal auditors especially for those that work in GLCs in Malaysia. It is to determine the internal auditors’ perception toward the effectiveness of internal audit activities, influenced by the individual factors related to the internal auditors themselves. This study also aims to determine the relationship between factors that contribute to the effectiveness. 300 questionnaires were distributed to internal auditors that work in GLCs in Malaysia using convenience sampling method, of which, 124 internal auditors had responded. Several statistical techniques such as the descriptive statistic, correlation and regression analysis were used to analyse the data from the survey. The result of the study showed that there were significant relationships among the factors analysed in this study which are the internal auditors’ competency, usage of information technology (IT) and career expectation. Hence, the effectiveness of internal audit will depend strongly to the attributes of the factors analysed in this study. This study will help organisations especially GLCs in understanding the factors that influence the internal auditors’ effectiveness and taking necessary action to improve their internal audit function. Consequently, the internal audit function could perform better in reporting findings and giving significant recommendations that give impact to the organisations.