Bernstein also claimed the FA had not started the search for the 65-year-old Italian's successor, adding: "You can't be half-pregnant on these things."
Responding to speculation that some within the FA are keen for Capello to extend his contract, Bernstein told the Leaders in Football conference in London: "One day he's going to go next week, the next day he's going to stay for 20 years.
"The position is very clear. He is our manager until the end of the European Championships. That is it."
On the search for a successor, he added: "It is not something on our agenda at the moment. You can't be half pregnant at these things."
Bernstein also insisted the FA were determined to learn the lessons from England's 2010 World Cup failure and would not keep the team isolated in their hotel during Euro 2012.
He suggested the squad would follow the example of World Cup runners-up Holland, who visited Robben Island - where Nelson Mandela was imprisoned - during their month in South Africa.
Bernstein said: "There are many lessons to be learnt from last year's World Cup experience and, believe me, these are being taken fully on board.
"We are placing far greater emphasis on what we can do to provide an enjoyable environment and experience at tournaments.
"We are determined our teams will fully embrace being involved at World Cups and European Championships, be good tourists engaging with fans, staying more centrally and not being isolated."