A transit bus (US), also known as a commuter bus, city bus, or public bus, is a bus used for short-distance public transport purposes. The roles and specifications of transit buses are not clear cut, and vary with operator and region.

With the development of bus building technologies and urbanisation, the emergence of specific transit bus features emerged for the different operating conditions compared to other private or public transport bus use.

The features of a transit bus are geared for operation on regular urban or suburban bus routes, with multiple defined stops, in a commuting or short-distance leisure role. This is as opposed to all-seated inter-urban or long-distance coach public transport; shuttle buses; demand-responsive buses such as paratransit, or private-hire bus or coach operations. Increasingly, transit buses are built as low-floor vehicles.

Generally, a transit bus will have:

Modern transit buses are also increasingly being equipped with passenger information systems, multimedia entertainment/advertising, and passenger comforts such as heating and air-conditioning (as opposed to historically where actually necessary). Some industry members and commentators promote the idea of making the interior of a transit bus as inviting as a private car, recognising the chief competitor to the transit bus in most markets.