Currently, only freight trains use the track.
The railway line, which ceased passenger service in 1902, could be reopened as the West London Orbital.
The Dudding Hill Loop runs from Acton to Cricklewood and is currently operated only by freight trains.
TfL estimates it is used by more than 11 million people a year.
TfL says new stations will be added to existing lines.
New stations will be added to the Dudding Hill line, as well as platforms and facilities added to other existing stations along the line.
West London Business’s Andrew Dakers said the track could create 120,000 jobs and potentially 16,000 homes along the route.
“Given local housing costs, more housing would be a good thing,” he said.
Proposed WLO routes and connections
Sharma Tatler, deputy leader of Brent Council, said the plans were a “no brainer”.
She said: “As the plans already exist, the investment will not be as large as other projects, so it will not mean much disruption for residents and businesses, and it will actually mean that the private sector and public funds can also be leveraged to invest. Masu” .
“This land is not publicly owned, so we need private investors to support our ambitions here.”
TfL said the service could start in the early 2030s if funding is identified and plans approved.