A contract has been awarded to begin infrastructure works for Jeddah Tower and Jeddah Economic City.
Al Fouzan Trading and General Construction Company has won the $165.3m (SAR620m) contract, and is expected to complete its work within 12 months.
Jeddah Tower is touted to become the world's tallest building upon its launch.
The infra works contract was signed by Eng Talal Almaiman, chief executive officer of Kingdom Holding Company (KHC), and board member of Jeddah Economic City.
Commenting on the contract, Almaiman said: "This contract is one of the largest private[-sector] infrastructure contracts in the Kingdom of Saudi Arabia, and the signing of the infrastructure contract will open the doors to investment opportunities for all."
Mounib Hammoud, chief executive officer of JEC, added: "The implementation of the advanced infrastructure is considered an essential step in positioning this mega development as a world class project.
"The works are going according to the set time-frame and soon, plots of land will be available and ready for development by local [and] international investors with all support services and utilities that include state-of-the-art infrastructure, district cooling, gas networks, streets furnishings and finishing, generous public open spaces, gardens, and other elements of an environmentally friendly smart city."
Hammoud said Jeddah Economic City would offer "the tallest tower in the world, a sustainable mixed-use environment, residential apartments for most budgets, a tourism, retail, and leisure destination, and a business centre".
"The Jeddah Economic City project will anchor the growth of Jeddah and will offer thousands of job opportunities for young Saudis in various fields," he added.