Pupils from three primary schools presented a cheque to a charity after months of fundraising.
The schoolchildren from Heathland School, in Eastcote Lane, Pinner, Whitefriars School, in Whitefriars Avenue and St John Fisher, also in Pinner, raised more than £1,500 for Harrow Mencap since April.
The charity was chosen by the pupil council’s of each of the schools and during the past few months she schools have held non-uniform days, discos and supermarket collections.
Heathland School deputy headteacher Steven Deanus said: “It’s been really nice for the children to pick their own charity and learn about their wider community.
“It’s a great achievement from all the children to raise so much and It has been a fantastic opportunity for them find out more about those in need. We’re very proud.”
The charity, which has been working in the borough for decades, supports of people across area with learning disabilities and their families.
Harrow Mencap chief executive Deven Pillay said: “It is absolutely marvellous that the children picked us as their chosen charity.
"It’s very heartening to know young people are taking an interest in what is going on in their local community and want to help those who are vulnerable."