The Dance-based Interdisciplinary Approach (DIA) integrates dance with music and other subjects to foster students’ creativity, cognition, and collaboration. Although the 2022 Arts Curriculum Standards advocate cross-arts integration, the implementation of DIA in Chinese public schools remains limited, and mechanism-based evidence is lacking. This study adopted an explanatory mixed-methods design to examine Shanghai public-school music teachers’ acceptability, intention, and implementation of DIA: quantitatively, a TAM-based survey of 105 teachers; qualitatively, semi-structured interviews with nine teachers. Results indicated that teachers held positive perceptions of usefulness (M = 3.26) and easy of use (M = 2.64), but reported low actual use (M = 1.51), revealing a “high endorsement-low implementation” paradox. Regression and mediation analyses showed that perceived ease of use does not directly predict implementation; only when it enhances perceived usefulness does it translate into classroom practice. Furthermore, a dance-major background significantly increased the likelihood of implementation, while music-major teachers tended to employ dance primarily as a supplementary tool for rhythm and emotion. Qualitative findings further illustrated differences in integration pathways and assessment emphases between the two groups. This study provides mechanism-level evidence with cross-cultural relevance: bridging the cognition-practice gap hinges on highlighting demonstrable instructional value (usefulness) and supplying ready-to-use lesson packages and assessment tools. Such a dissemination framework is equally applicable to international music education systems operating under diverse policy and resource conditions.