England, Wales and Northern Ireland will all be competing at the football showcase in France which kicks off on Friday.
And the Prime Minister has outlined his hope that the UK’s nations will support each other.
Speaking during Prime Minister’s Questions, he said: “I’m sure this is one occasion when the whole House will want all the home nations to stay in Europe for as long as possible.”
Mr Cameron was looking towards SNP MPs as he spoke and members across the House then started to laugh.
A grinning Mr Cameron continued: “Come on. I’m going to be watching.
“Our first game is England-Russia and I’m going to be watching very carefully to check we get very strong support.”
Mr Cameron was responding to a question from DUP MP Nigel Dodds (Belfast North) who said that people from across the UK, including Scotland, will be travelling to the tournament.
He asked the Prime Minister to ensure that the British embassy and consular staff in France are prepared to help Britons, should the tournament be targeted by terrorists.
Mr Cameron said: “We have set out very clear travel advice because people do need to know that obviously there is a significant terrorist threat in France today and there is a potential threat to this tournament.
“We have set out very clearly the threat level in France is critical, the threat level for the tournament is severe and people need to know that.
“The French security operation is enormous: 77,000 police and gendarmes, 10,000 military personnel, 13,000 security guards.
“We are providing additional counter terrorism and public order support to the French including deployment of additional police on trains into France, more UK Border Force outbound checks and we are also helping with sniffer dogs and any other areas that the French ask us for.
“We all want to see an absolutely great celebration of European football. I wish all the home nations well.
“I think it’s brilliant that Northern Ireland have made it to this tournament and of course Wales and of course England.”