Disclosed are a vehicle-mounted audio playing method and apparatus, a multimedia host, and a storage medium. The vehicle-mounted audio playing method includes: obtaining, by the multimedia host through a receiver, a first voice signal collected by a mobile microphone; and when the vehicle-mounted audio playing apparatus is in an out-of-vehicle karaoke mode, fusing, by the multimedia host, the first voice signal and an accompaniment signal, and outputting a fused signal to an out-of-vehicle speaker after performing amplification processing through a power amplifier, to drive the out-of-vehicle speaker to produce sound.