6 Hillgrove won the account following a pitch. The work was previously managed in-house at Clarks.
Soul of Africa is a project that helps families affected by Aids and creates sustainable employment in Africa. The charity teaches people to make shoes using local materials, with money from sales going towards education and care for orphans and families.
The shoes are sold exclusively in Clarks.
Richard Hillgrove, founder of 6 Hillgrove, said: "Soul of Africa is boldly defining the new Africa, a progressive Africa that is throwing off the welfare-dependent stereotype. It's all about aid through enterprise. The new shoe launching in the summer in Clarks encapsulates the sea change that is going on."
Clarks' global PR account was won by Mary Portas' comms agency, Portas, in January.