Under Mr. Fitzsimmons' leadership, the IESO oversees the operation of Ontario's bulk electricity system, ensuring reliable, affordable, and sustainable electricity is available when and where people need it, while supporting energy development that drives economic growth.

Mr. Fitzsimmons has extensive experience in both government and the energy sector. Prior to joining the IESO, he served as Ontario's Deputy Minister of Finance and Deputy Minister of Energy, where he helped advance the province's energy and economic priorities.

Mr. Fitzsimmons joined the government from the C-Suite at Hydro One where he held the role of Chief Corporate Affairs and Customer Officer. With more than 30 years of experience in the energy sector, Mr. Fitzsimmons has held a number of executive positions at both Hydro One and Ontario Power Generation.

Throughout his career, Mr. Fitzsimmons has led large-scale organizational initiatives, driven strategic transformation, and championed customer-focused service delivery and progressive economic partnerships with First Nations. He is recognized for building enduring and meaningful relationships with Indigenous communities, industry, government, labour organizations, and other sector partners, fostering growth, innovation, and collaboration.

In 2020, Mr. Fitzsimmons was recognized as one of Canada's 50 Best Executives by The Globe and Mail's Report on Business for his leadership in guiding transformational change while delivering industry-leading customer support programs.

Mr. Fitzsimmons was the past Chair of the Ontario Financing Authority and the Ontario Electricity Financing Corporation, and served as a commissioner on the Public Service Commission of Ontario. He has also served as Chairman of Acronym Telecom and as an Independent Director on the Board of Directors for the Electrical Power Systems Construction Association and the Electricity Distributors Association. Mr. Fitzsimmons is deeply committed to advancing public policy and was an active member of Western University's Ivey Energy Policy Advisory Board and Toronto Metropolitan University's Centre for Labour Management Relations Advisory Board.