Inferno won the business after a three-way competitive pitch in a process that started last month.
The appointment ends the NSPCC's long-standing relationship with its incumbent, Rapp. The agency had worked on the NSPCC account for 12 years and had been behind the activity for the charity's high-profile "Full Stop" and ChildLine campaigns.
Inferno's appointment strengthens its current relationship with the charity, which began earlier this year when it was hired to oversee the NSPCC's ad account for its Helpline service.
Now Inferno will be responsible for handling all of the NSPCC's fundraising activity, including DRTV across its ChildLine service, with campaigns expected to launch at the end of the year.
The NSPCC's media account is also under review.Follow @SaraKimberley