Amess is a staunch Eurosceptic, coming out in support of Brexit ahead of the EU referendum, in which he said it was "dangerous" and a "huge mistake" to vote 'remain'. He has described a "loss of Parliamentary sovereignty" as the main negative of UK-EU relations. Amess criticised US President Barack Obama's perceived intervention in the EU referendum campaign, stating that he had "absolutely no right whatsover getting involved". Since the Brexit vote, he has been a keen supporter of Leave Means Leave, signing a letter to the Prime Minister in September 2017.