Joanna Lumley has agreed to become the ambassador for the Child Welfare Scheme charity based in Loman Street.
CWS, a small charity supporting children at risk in Nepal, is one of the few western charities which remained in Nepal during the recent conflicts.
"I have been inspired by the work that CWS does supporting some of the most disadvantaged and marginalised children in Nepal," said Joanna Lumley who is in Nepal receiving a rapturous welcome after successfully securing the right of Gurkha soldiers to settle in Britain.
She added: "I hope that my involvement with CWS will help to make a positive difference to their lives and future".
Delighted charity chief executive Steve McCall, speaking in Southwark, said: "Joanna will undoubtedly help to raise our UK profile and boost our fundraising efforts. I am sure her involvement will help to take us to the next level and enable us to do even more for the thousands of disadvantaged children and their communities that we are trying to help in Nepal."
CWS works with local partners to help over 30,000 children and young people in Nepal. This includes those at risk of or who have been trafficked, street children, those involved in child labour and who live in slum and mountain areas with little access to education, health or social opportunity.
CWS also supports work with pregnant women and young children and now collaborates with the Nepalese Government to deliver regional programmes such as immunisation and improved maternal care.