The year-long brief was awarded to House following a four-way competitive pitch.
The agency kicked off on Monday by launching Save The Children's 'No Children Born to Die' campaign, which is being fronted by pop star Alexandra Burke. The campaign is addressing the issue of children under the age of five who are dying from preventable diseases around the world.
House PR director Sam Oxley said: 'It's about providing scale and impact for this campaign. The main challenge is we've got to compete with other high profile campaigns, like Comic Relief.'
House PR will manage a varied calendar of PR events including digital engagement, news generation and press office support.
Save The Children head of PR Kate Redman said: 'We are confident the team can deliver a strategic campaign to maximise awareness of our work and help motivate the public to join us in stopping the needless deaths of children around the world every year.'
The charity's recent campaigning work has focused on children affected by the conflict in Gaza, and the effect of growing up in the UK in low-income families.
House PR was awarded the business following a pitch that focused on delivery of online and offline media, arts-based interactive engagement as well as stunts, celebrity engagement and events.