Her brief is to work closely with WPP's operating companies to create disciplined personnel management practices and build an environment that helps people to flourish.
The group chief executive, Sir Martin Sorrell, said: "The critical differentiator in our industry is the quality of our people. Beth's business strategy, personnel management and organisational background will add leadership and insight to our talent-building efforts."
"Her appointment will clearly enable us to raise our game as we put talent at the centre of our agenda and make WPP a more distinctively attractive place for talented people in our industry,
Brooks is currently part-way through his 12-month gardening leave, having accepted an offer last November from Interpublic's chief executive, John Dooner, to become that company's head of human resources.
Axelrod said: "I am delighted to join a global organisation with exceptional people, a strong performance orientation and a priority on building the strongest pool of industry professionals."