In 2001, after graduating, Fitzpatrick founded The Rental Guide, a real estate advertisement business which promoted properties in Scotland online and via a free newspaper. Livewire nominated him for the Young Entrepreneur of the Year. Fitzpatrick closed the business due to concerns about its ability to scale given limited numbers of real estate agents. He moved to London to take jobs in the financial sector with Societe Generale and JP Morgan.
OVO Energy
Fitzpatrick founded OVO Energy in 2009. The company was the culmination of a five-year plan during which he received a licence from Ofgem, the UK energy regulator, and saved the £350,000 to start the business. As of July 2016, the company served 685,000 customers and employed over 1,000 people in Bristol and London. He acknowledged his inexperience with the energy market, and used the five years to study the industry; he credited the experience he gained with complex finances during those five years as critical to the company's survival. In 2014, Fitzpatrick won Entrepreneur of the Year at the National Business Awards. In 2018, Fitzpatrick led OVO Energy in the successful acquisition of one of its competitors, Spark Energy.
In autumn 2013, Fitzpatrick testified before Parliament's Energy and Climate Change Select Committee on the subject of rising energy prices. He testified that he could not explain why the "Big Six" energy suppliers, the six largest providers of gas and electricity in the United Kingdom, raised prices. He also noted that Ovo's prices had not increased because the wholesale cost of energy to suppliers remained unchanged. The BBC credited Fitzpatrick's testimony with being one of the drivers behind a 2014 Ofgem investigation into whether the market-dominating Big Six negatively limited competition.
Use of company funds
In 2014 Fitzpatrick sold OVO stock to raise £2 million or 4.5% of the company to purchase his family home. The move drew criticism from The Guardian newspaper because in the previous year the company earned only £300,000 and had £9 million in liabilities.
Imagination Industries
Fitzpatrick is the sole owner of Imagination Industries Ltd, a holding company which has OVO Energy among its subsidiaries alongside many smaller companies in retail energy supply and related businesses such as electric car charging. Three of the energy supply subsidiaries operate in Australia, France and Germany. Another subsidiary, Vertical Aerospace Ltd, develops electrically powered VTOL aircraft.
Fitzpatrick, a self-described lifelong Formula One enthusiast, became owner of and a major investor in the Manor Marussia Formula One team in 2015, taking over after the collapse of the team's previous parent company. Partnering with former Sainsbury's executive Justin King, who joined as interim chairman but did not directly invest in the team, Fitzpatrick contributed £30 million in personal funds to Manor Marussia and re-built the team run by Graeme Lowdon and John Booth after some of its assets had been auctioned off to repay the debts. On 6 January 2017 it was reported that Manor Racing had entered administration, and were on the verge of collapsing. On 27 January 2017, the team collapsed after administrators failed to secure a sale of the business.