The project is a departure from the council’s development plan and will need consent from communities secretary Eric Pickles before it can proceed.
A report to its planning committee noted: "It is recommended that the benefits of the proposal are substantial and outweigh the harm identified and the conflict with elements of the development plan."
Applicants Inox and Exemplar Projects (Truro) want to build the stadium adjacent to Truro’s park and ride site at Threemilestone to provide an arena for local football and rugby clubs.
The planning report said: "The stadium in particular has the potential to be a landmark building and exemplar project for Cornwall.
"A high quality design is being promoted in the design and access statement to reflect its status and to help ensure the expected economic and regeneration benefits are delivered."
Campaign group Stadium for Cornwall has backed the project, citing a lack of large sports facilities in the county.