Pupils from Bishop Wood School in Tring joined more than 7,000 other youngsters singing in a mass choir at the O2 Arena.
Five months of rehearsals culminated in teachers and parents accompanying 122 pupils to the London venue for Young Voices 2014, where they performed several medleys and got the chance to be backing singers for X Factor star Stacey Solomon.
Music coordinator Janet Reeve said: “The children were a credit to the school. They behaved really well and sang enthusiastically. The whole show was unforgettable and the parents commented on how great it was.”