The OAuGF is a constitutional body in Nigeria, created by the Constitution of the Federal Republic of Nigeria 1999 (as amended), particularly Sections 85, 86, and 87, which define its existence, powers, duties and the procedure for appointing the Auditor-General.Its role is to audit all public accounts of the Federation and all offices and courts of the Federation and to report to the National Assembly.

Among its primary functions are: financial audits of government income and expenditures to ensure they are lawfully kept and faithfully expended; appropriation audits to check whether funds are used as approved by the National Assembly; compliance with rules and procedures (e.g. tendering, storekeeping etc.); value-for-money (performance) audits; and periodic checks on statutory corporations, commissions, authorities, agencies established by law, to ensure they adhere to accounting and financial regulations.