Official corruption remain one of the major challenges of Nigeria and has become deep-rooted in her public sector administration leading to severe consequences to the country’s economic and socio-political development. Public financial probity and accountability are promoted partly through the conduct of regular audits by the office of the Auditor- General, recognized as the Supreme Audit Institution (SAI) of any country. The Auditor General Office is expected to serve as a corner stone for good public sector governance through the provision of unbiased objective assessments of whether public resources are responsibly and effectively managed to achieve intended results. How effective has the Office of the Auditor General of the Federation of Nigeria been able to discharge her responsibilities, particular with respect to the curtailment of corruption in government and what possible challenges could be militating against this Nigerian Supreme Audit Institution and in what ways and means could these challenges be overcome are the preoccupations of this paper? Through in-depth literature review and analysis of secondary data this paper traces the principal challenges of Nigeria’s Auditor-General Office to include the issues of independence, capacity building, political will of the Executive and the legislature to implement the Auditor-General’s report. The paper finds the effectiveness of the Auditor General’s Office and the curtailment of official corruption to lie squarely with the sincere and effective efforts towards the resolution of these challenges by the Government of Nigeria.