Based on the panel data of 108 cities in the Yangtze River Economic Belt from 2010 to 2022, this paper employs the fixed effect model, threshold effect model, and spatial Durbin model to systematically investigate the impact of new quality productive forces on the high-quality economic development of the Yangtze River Economic Belt. The findings of this paper are as follows. Firstly, the new quality productive forces significantly promote the economic quality improvement of the Yangtze River Economic Belt, and the effect shows obvious regional differences, which is manifested in the more significant effect on the upstream areas, high-level development areas, and large-scale cities. Secondly, the nonlinear dynamic impact of new quality productive forces on the high-quality economic development of the Yangtze River Economic Belt is positive and has an increasing “marginal effect”, which strengthens with the improvement of its development level and industrial structure. Thirdly, the new quality productive forces can not only enhance local economic quality but also significantly boost economic development in neighboring regions through spatial spillover effects. To facilitate new quality productive forces in empowering high-quality economic development in the Yangtze River Economic Belt, it is essential to advance technological innovation for accelerating the formation of new quality productive forces, implement differentiated development strategies tailored to local conditions, and optimize industrial structures to achieve regional coordinated development.