The Stadio della Roma project was given the green light earlier this month by Raggi, after it received the backing of an independent technical report into how the new venue would affect the surrounding area.
Now the head of the local government has confirmed how much funding will be needed to finance the project.
"The stadium will be built," Raggi told Italian daily La Verita.
"Our proposals have already been approved and we've ensured they meet very high environmental standards.
"The experts at Politecnico di Torino have only confirmed that. The area identified for the stadium is the right one: after that, it's clear that there must be a structure which doesn't serve only cars.
"There are two railway lines that still need to be upgraded. We've signed a deal with Ferrovie dello Stato for a general renewal of the rail lines.
"We're going to invest €1 billion of private funding over the next three years. This further highlights the fact that we support the project, regardless of its infrastructure."