Autonomous buses can improve the efficiency of public transportation and offer great benefits for developing sustainable mobility transportation. To realise the potential of autonomous buses in public transportation, understanding the public’s intention to use the new technology-based mobility concept is necessary. Therefore, this study synthesises three theories to explain public intention to use autonomous buses, namely, unified theory of acceptance and usage of technology (UTAUT), task technology fit (TTF) theory and trust theory. A survey instrument (n = 277) is adopted to validate the theoretical model. The results indicate that (1) performance expectancy (e.g., economic benefits, environmental friendliness and safety), effort expectancy (e.g., ease to use, availability and accessibility), social influence (e.g., attitudes of around people and information from society) and perceived risk (e.g., injuries, damages and privacy issues) lead to the formation of trust; and (2) trust has direct and indirect (via TTF) effects on behavioural intention to use autonomous buses. Furthermore, bootstrapping analysis is conducted, and the significance of the mediation effect of TTF is verified. The findings enrich the existing theoretical research on the adoption of autonomous buses and guide the future integration of autonomous buses into the public transportation system.