In a keynote speech to an audience of investors, architects and officials at the MIPIM Asia conference, Leroy said the French government was committed to the biggest redevelopment project Paris has seen in 150 years.
The 10-year scheme includes a €20-billion ($27 billion) 150-kilometre driverless subway around the French capital, and the construction of 70,000 new homes a year, he said.
Leroy, who is overseeing the 34-billion-euro project, compared the French government's clarity of purpose with China's vast urban development projects, which have transformed cities such as Shanghai over the past decade.
"Greater Paris is an economic ambition backed by political will at the highest level of the state," he said, referring to a 2010 law and the support of President Nicolas Sarkozy.
"Whatever happens in the French political environment, it will not be in doubt."
He said that despite the economic crisis gripping Europe, investors could have confidence that the Paris renewal project had all the legal and financial support of the state.
Ten teams of foreign and French architects are already working in parallel to "create a shared vision of the city of tomorrow," Leroy added.
The project also envisages the redevelopment of the Seine river, which runs under Paris's famous bridges, as a major transport link to the Channel port of Le Havre.
Work on the new transport system is expected to begin next year.