Justin Forsyth joins from working for former prime minister Gordon Brown and before that, Tony Blair.
During his time at Downing Street, Forsyth co-ordinated the comms strategy around last year’s G20 summit in London.
Forsyth has also worked as at Oxfam for 15 years, latterly as the director of campaigns and policy. He also helped to establish the Make Poverty History campaign.
Save The Children aims to save 5 million children’s lives a year.
Forsyth said: ‘We can – and must – stop these needless deaths, and ensure that every child gets a chance in life, wherever they are born in the world.’
Save the Children executive chairman Alan Parker said: ‘This is a critical period for Save the Children UK. We have made great progress in recent years but the challenge of supporting children abroad and at home continues to grow.
‘Justin brings enormous experience and commitment and I have no doubt he will make a real contribution to driving the organisation forward.’