He will be based in the Dubai office.
Mr Legg was IMS director for Carillion MENA . Before that he worked for Wilmott Dixon and Skanska, where he was the UK EHS director.
He has represented the industry on the CITB health and safety committee, the UK Health & Safety Executive industry safety programmes and is a member of several strategic international safety bodies.
Mace head of health and safety Andrew Brown said: “Ben’s appointment marks a new stage in the growth and development of Mace and in particular, provides a focus for the on-going development and application of health and safety in our international operations.”