Frank PR, Grayling and MSLGroup London will work alongside the PR division of the fourth agency, digital marketing and technology consultancy Amaze. Amaze is also the NSPCC's digital partner.
The agencies will have the opportunity to pitch to work alongside the NSPCC’s in-house teams on campaigns such as the festive fundraising product, Letter from Santa, and awareness campaigns such as The Underwear Rule.
Work will be awarded on a project-by-project basis, and the roster will be formally reviewed in July 2015.
NSPCC director of comms Ali Jeremy said: "We’re delighted to have these four fantastic agencies on board and look forward to working with them over the coming months to drive our national fundraising and campaigning activity and make a real difference for vulnerable children here in the UK."