The integrated campaign, created by Touch DDB, includes a four-part viral charting the most pivotal periods in the charity's history.
The film covers the year that Save the Children was set up in 1919, World War Two, the period in the 1970s when the charity became a household name and the present day, where Save the Children has become a global organisation helping to provide aid in response to international crises such as the 2004 tsunami in Asia.
It aims to show how supporters' money has helped the charity develop during its 90-year history, and highlights the work that Save the Children has done to change the lives of young people.
The viral will be supported by a direct marketing pack that will be sent to existing supporters of the charity, encouraging them to amend their wills to leave Save the Children a legacy donation.
The campaign marks the first time that Save the Children has invested heavily in legacy marketing.
The charity appointed Touch DDB to work on the account in March last year, following a pitch against undisclosed agencies.