Cairns supported remaining in the European Union in the 2016 UK European Union membership referendum. In the campaign period leading up to the referendum, in a government pamphlet sent to all homes across Wales, he stated: "One thing I think we can all agree on is that Europe needs reform. The Prime Minister has fought hard to get a deal which gives the UK the protections it needs." He further stated that the UK had achieved "a special status" within Europe and how the deal negotiated would allow Britain to avoid "the Euro, open borders or the prospect of ever-closer union."