Audit firms play a critical role in Nigeria’s corporate sector by independently examining and verifying financial records to ensure accuracy, regulatory compliance, and stakeholder assurance.

Other News

In 2025, seven audit firms generated a combined revenue of N37.08 billion, up from N28.76 billion in 2024.

These revenues were earned from auditing major listed companies such as Zenith Bank, UBA, Access Holdings, Transcorp, Seplat, and Dangote Cement, as well as non-listed firms with annual turnover exceeding N100 billion, otherwise known as NMX 100.

The growth reflects the increasing complexity of corporate financial reporting and the demand for professional assurance services among high-turnover organizations.

While the metrics focus on companies with turnover above N100 billion, the audit firms also serve other clients not listed on the Nigerian Exchange Limited (NGX) or with smaller turnovers.

Below is a list of the seven largest audit firms in Nigeria for 2025, based on their earnings from the largest NGX-listed companies.

SIAO Partners – N31.5million

SIAO Partners generated N31.5 million in revenue in 2025, derived solely from auditing MRS, the only company under its portfolio for the year.

Founded in 2005 through the merger of four audit firms, SIAO Partners is a prominent Nigerian professional services firm providing audit, tax, accounting, and advisory services to both local and international clients. The firm is headquartered in Ikoyi, Lagos, and has built a reputation for delivering high-quality professional services.

The name ‘SIAO’ represents the founding partners—Smith, Ighodalo, Adewale, and Odiachi. The firm employs over 150 professionals, offering both local insight and international expertise to its clientele.

Despite the small revenue figure relative to other top firms, SIAO Partners continues to maintain a focused and specialised client base.

Grant Thornton – N79.67million

Grant Thornton Nigeria posted N79.67 million in revenue for 2025, a 5.8% increase from N75.30 million in 2024, mainly from auditing 11 Plc (formerly Mobil Oil Nigeria Plc).

As part of a global network, Grant Thornton provides accounting, tax, advisory, and consulting services across more than 147 markets worldwide.

It is ranked as the sixth-largest professional services network in Nigeria by revenue and serves a diverse set of clients, including publicly listed companies, private businesses, and public sector entities.

The firm is recognised for its robust professional services and adherence to international standards, making it a trusted partner for corporate governance and regulatory compliance in Nigeria. The Nigerian operation plays a strategic role in executing global best practices in auditing and consulting.

ForvisMazars – N136 million 

Forvis Mazars earned N136 million in 2025, exclusively from auditing Unilever Nigeria, representing a 56.6% increase from N86.88 million in 2024.

The firm is part of a leading global network providing audit, tax, and advisory services in over 100 countries, with a workforce of approximately 40,000 professionals. Mazars has a strong reputation for delivering quality financial oversight to multinational corporations and domestic clients alike.

This growth in revenue reflects the increasing complexity and scale of operations at Unilever Nigeria, alongside Mazars’ ability to manage large, high-profile clients efficiently. The firm’s expertise ensures regulatory compliance and financial accuracy across its engagements.

Deloitte – N2.41billion

Deloitte generated N2.41 billion in 2025, marking a 17.6% increase over N2.05 billion in 2024, auditing Fidelity Bank, Transcorp, and Custodian Investment Plc.

Revenue contribution included N1.89 billion from Fidelity Bank, N353 million from Transcorp, and N167 million from Custodian Investment.

Deloitte is a British multinational professional services network offering audit, consulting, financial advisory, risk, tax, and legal services across over 150 countries.

Deloitte’s strong presence in Nigeria ensures comprehensive financial and advisory services for some of the country’s largest corporations, reinforcing its status as part of the ‘Big Four’ accounting firms. The firm combines international expertise with local insights to deliver impactful results for its clients.

PwC – N9.32billion

PwC recorded a revenue of N9.32 billion in 2025, up 8.8% from N8.57 billion in 2024, serving 17 clients including Zenith Bank, Seplat, Stanbic IBTC, Julius Berger, and BUA Cement.

Zenith Bank was PwC’s largest client, contributing N3.12 billion, followed by Seplat with N2.67 billion and Stanbic IBTC at N1.06 billion.

PwC operates in over 130 countries globally and is renowned for its high-quality assurance, tax, and consulting services.

The firm’s large client base underscores its prominence in Nigeria’s audit sector, combining extensive experience with deep understanding of local regulatory frameworks and market dynamics.

PwC’s footprint in Nigeria continues to expand as the demand for professional auditing services grows among high-turnover companies.

EY – N9.48billion

Ernst & Young (EY) earned N9.48 billion in 2025, up 16.3% from N8.15 billion in 2024, serving 10 clients including UBA, GTCO, MTN Nigeria, WAPCO, Nestle, and Okomu Oil.

UBA was the largest contributor, providing N4.97 billion in revenue, followed by GTCO with N3.09 billion and MTN Nigeria with N794 million.

EY is a multinational professional services network headquartered in London, UK, and part of the Big Four, offering assurance, consulting, strategy, and tax services worldwide.

Founded in 1989 through the merger of Ernst & Ernst and Arthur Young & Co, EY leverages global expertise and local knowledge to deliver reliable audit and advisory services, maintaining high standards of corporate governance and financial transparency.

KPMG – N15.62billion

KPMG was the top-earning audit firm in Nigeria for 2025, generating N15.62 billion, a 59.4% increase from N9.8 billion in 2024.

The firm served eight clients including Access Holdings, First HoldCo, UAC Nigeria, Dangote Cement, Presco, Wema Bank, NEM Insurance, and Nigerian Breweries.

Access Holdings was the largest contributor, with N8.7 billion in revenue, followed by First HoldCo at N3.96 billion and Dangote Cement at N1.8 billion.

KPMG operates in 142 countries, providing audit, tax, and advisory services, and is a member of the Big Four global accounting firms.

The name ‘KPMG’ originates from the merger of Klynveld Main Goerdeler and Peat Marwick in 1987, reflecting a long legacy of professional service excellence.