The bus will be used without a driver in depots for manoeuvres such as parking, fuelling and washing.
The company, which is helmed by Brian Souter, said legal restrictions prevent the vehicle being used without a driver when passengers are on board but in future the technology is expected to be used more widely.
Stagecoach has joined bus manufacturer Alexander Dennis Limited (ADL) and technology company Fusion Processing to create what it says is the UK’s first full-size driverless bus.
It is being built at ADL’s site in Guildford, Surrey, and is expected to be in use later this year.
The transport operator said sensors in place to enable driverless journeys also help improve safety when a driver is behind the wheel, by warning of cyclists of pedestrians in blind spots or unexpectedly close to the bus.
The system uses several sensors - including radar, laser, camera and ultrasound - along with satellite navigation to detect and avoid objects and plan routes.
Sam Greer, Stagecoach UK bus engineering director, said: “Stagecoach has long been at the heart of innovation within the bus industry and this is an exciting trial that will deliver the UK’s first fully autonomous single deck bus.
“We look forward to working with our partners on this project which we believe could, in time, help improve safety and efficiency within our depots, and over the longer term, help transform bus travel in the future.”