Boles supported the Remain campaign in the European Union membership referendum in 2016. After the referendum vote to leave the EU, he favoured a Norway-style relationship between the UK and the EU after Brexit, and strongly opposed a no-deal Brexit. Boles said in December 2018 "if at any point between now and 29 March [2019] the government were to announce that 'no deal' Brexit had become its policy, I would immediately resign the Conservative whip and vote in any way necessary to stop it from happening."
