Baker campaigned for Brexit before and during the 2016 referendum. He says he originally joined the Conservative Party with the express intention of campaigning for the UK to leave the EU. He chaired Conservatives for Britain, a predecessor group to the official Vote Leave campaign and the Eurosceptic European Research Group until becoming a minister. He was described by the "New Statesman" as someone who had been "the most doctrinaire Leaver inside government and one of the few sincere advocates for a no-deal exit on the government payroll" before resigning. Back in 2010, he stated at a meeting of the Libertarian Alliance that he thought "the European Union needs to be wholly torn down", considering it "an obstacle to ... free trade and peace among all the nations of Europe as well as the world". Baker argues Brexit presents an opportunity for more free trade outside the EU but also favours protectionism against China. During an interview with Sky News after a debate on Brexit in April 2019, Baker referred to himself as "the hard man of Brexit".