Atedo Peterside founded Investment Banking and Trust Company Limited (IBTC) in 1989. The company underwent several mergers, eventually becoming Stanbic IBTC Holdings Plc in 2007. From 1989 to 2007, Peterside served as the CEO of the bank and then transitioned to the role of Chairman from 2007 until September 2014. He continued to serve as the Chairman of Stanbic IBTC Holdings Plc until March 2017.
He is currently a Director of The Standard Bank of South Africa Limited and Standard Bank Group Limited.

Peterside serves as the Non-Executive Chairman of Cadbury Nigeria Plc. He is also a member of the Board of Directors of Flour Mills of Nigeria Plc, Nigerian Breweries Plc (Heineken Subsidiary) and Unilever Nigeria Plc. He was the Chairman of the Committee on Corporate Governance of Public Companies in Nigeria, which crafted the first Code of Best Practices for Public Companies operating in Nigeria. The Code was published in October 2003.

He served as an independent director of Presco plc and a non-executive director of Lekoil Limited. He was the director of Mobil Oil Nigeria plc. He also served as Director of FSDH Merchant Bank Limited.
Peterside was a member of the National Council on Privatisation (NCP) from 2011 to 2015. He was also the Chairman of the NCP's Technical Committee. In that capacity, he oversaw Nigeria's power sector privatisation programme, which culminated in the privatisation of all the electricity distribution companies in Nigeria and virtually all the generation companies which were previously a part of the Power Holding Company of Nigeria. He was also a member of the National Economic Management Team.

In May 2017, Peterside was appointed as the Alternate Private Sector Vice-Chairman of the Nigerian Industrial Policy and Competitiveness Advisory Council.

He is the Founder and President of ANAP Foundation, a non-profit organisation committed to promoting Good Governance. He is a Member of the Committee for the Revitalisation of the Nigerian Economy. He regularly comments on the Nigerian economy and the domestic financial system. He is a Fellow of the Chartered Institute of Bankers of Nigeria and is a Member of the Council of the Chartered Institute of Stockbrokers.