This study investigates the effectiveness of internal audit functions in preventing corporate fraud in Nigeria, focusing on three critical dimensions: audit independence, audit competence, and audit frequency and scope. The motivation for the study stems from the persistent incidence of financial misappropriation and fraudulent practices across various sectors in Nigeria, despite the presence of internal control systems. A descriptive survey research design was adopted, and data were collected from 182 internal auditors, compliance officers, and finance professionals using structured questionnaires. The data were analyzed using descriptive statistics and multiple regression techniques. The findings reveal that all three internal audit dimensions have a significant and positive relationship with corporate fraud prevention. Audit competence emerged as the most influential factor, followed by audit independence and audit frequency/scope. The study concludes that internal audit plays a pivotal role in reducing the incidence of fraud and enhancing the effectiveness of fraud detection mechanisms within organizations. The study recommends that organizations strengthen auditor independence by aligning reporting structures to the board or audit committee, invest in the professional development of internal auditors, and ensure comprehensive and frequent audit engagements. Regulatory bodies are also urged to enforce compliance with audit standards and support ethical governance practices. This study contributes to the literature on corporate governance and offers practical insights for strengthening fraud prevention frameworks in developing economies.