The firm confirmed that Muldoon and the board had agreed to part ways on an amicable basis in a senior management shake-up.
Muldoon will officially leave on Friday after 22 years with the business, which is owned by property giant Brookfield.
John Flecker, Multiplex chief executive officer for Australasia and India, will take over Muldoon’s responsibilities in the restructure that sees him appointed to the new position of global chief executive officer.
Flecker is a 32-year Multiplex veteran and has been involved in Multiplex’s global leadership for the past 10 years.
He will work closely with EMEC chief operating officer Callum Tuckett to ensure a smooth transition and an ongoing focus on outperformance across all operations.