Chisholm was previously the chief executive of the United Kingdom's Competition and Markets Authority and chair of the Irish Commission for Communications Regulation, and has held senior positions in the media, technology and e-commerce industries.

[2][3] He was privately educated at Downside School before studying history at Merton College, Oxford, and a Master of Business Administration degree at INSEAD.

[6] He left the role to become the first chief executive of the Competition and Markets Authority (CMA) in the United Kingdom, with his appointment announced on 8 January 2013.

[10] During a talk to the Institute of Directors, he defended the existence of regulators because "some market participants can ruin it for everybody" and that Bitcoin provided "welcome competition".

[11] In 2015, Chisholm wrote in a Financial Times article that proposed taxi regulations by Transport for London, following protests against ride-sharing firm Uber, would "artificially restrict competition".

[12][13] In 2016 he announced a CMA report that advocated abolishing passenger rail franchising to allow different companies to run services on the same routes.