The all-for-one tourism guides the development of the tourism industry in China and promotes coordinated development of the economy and society. Existing studies emphasize the significance of all-for-one tourism but pay limited attention to the impact and mechanism of all-for-one tourism on the high-quality development of tourism. By employing the all-for-one tourism demonstration zones as a quasi-natural experiment, this research uses the time-varying difference-in-differences (DID) model to empirically investigate the relationship between all-for-one tourism demonstration zones and the high-quality development of tourism. In particular, under the guidance of the new development philosophy, this research constructs a measurement and evaluation indicator system for the high-quality development of tourism from five dimensions, including innovative, coordinated, green, open, and shared development. The results show that the all-for-one tourism demonstration zones positively impact the high-quality development of tourism, and the result is robust to a series of robustness checks, including the placebo test and the propensity score matching (PSM) procedures. Network infrastructure construction and tourism talent agglomeration are mechanisms channelling through all-for-one tourism demonstration zones and high-quality tourism development. Heterogeneity analysis reveals positive impacts of all-for-one tourism demonstration zones on central and western regions and provinces with a low proportion of tertiary sector.