They were able to see the progress being made on site - including the Olympic Stadium and Aquatics Centre, two of the main new venues being built.
The children, who come from around the UK, signed up to the Children's Promise scheme aunched in 2004. They will play some role in ceremonies or events during the 2012 Games.
The Christmas tree was placed at the View Tube - a social enterprise and education venue at the Olympic Park where the public can come and learn about the London 2012 project.
Sebastian Coe, Chair of the London 2012 Organising Committee, said: 'The children and their families are on the journey with us as we work towards the summer of 2012.
'I’m delighted they enjoyed their day at the View Tube, which is not only a great viewing platform for the Olympic Park, but also an excellent educational facility for schools and community groups to use.
'I would like to wish all our Children’s Promise participants a very happy 5th birthday, a Merry Christmas and a Happy New Year!'
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