<p>High-quality development is the strategic choice and guiding principle driving China’s economy in the new era. Since high-quality economic development (HQED) is inherently continuous and dynamically evolving, this paper establishes a functional data analysis framework to quantify the temporal dynamics of regional disparities and spatial convergence in HQED. Firstly, this paper establishes a time-varying HQED index curve through the functional entropy weighting method, reflecting the provincial HQED continuous level. Then, the regional disparities in HQED are decomposed by applying the functional Gini coefficient, which reveals the source of these disparities. Finally, the paper examines the spatial correlation of HQED across provinces with the extended functional Moran index and investigates the spatial convergence trend from the process perspective by employing functional convergence models. Empirical results show that: (1) The HQED level is rising overall, with a spatial pattern of decline from the east coast to the northwest. (2) The regional disparities in HQED are primarily caused by inter-regional disparities, with innovative development as the main influencing factor in the southern coast and southwestern regions. (3) China’s HQED has a significant spatial correlation, with significant time-period characteristics in convergence trends. This paper reveals the evolving dynamics of China’s HQED, which both enriches the theoretical basis for quantifying regional disparities and the convergence trend of HQED and provides empirical support for policy formulation and regional development.</p> Graphic abstract <p></p>