Willby joins from Davis Langdon and worked with Mace on the London 2012 Olympic and Paralympic Games.
He has been involved in the delivery of international events and major sporting programmes, including The New Anfield, Green Point Stadium, Cape Town, (FIFA 2010 World Cup) and the City of Manchester Stadium for the Commonwealth Games 2002.
Managing Director of cost consultancy at Mace, Chris Goldthorpe, said: “With his reputation for managing high profile and complex sporting projects alongside design teams, Alan will be an asset to our business.
“His commitment to high quality delivery and knowledge share is in line with Mace’s own standards and practice of delivery.”
Willby, said: “I am delighted to be joining Chris and his team to help build upon the great success of London 2012 Olympic and Paralympic Games and to use my experience of major international projects to deliver intelligent high value services to clients and fellow professionals around the world.
“I am excited by the challenge ahead and at the prospect of working with so many talented and dedicated colleagues.”