Based on the data of 78 cities in the Yangtze River Economic Belt from 2010 to 2020, this study constructs an indicator system from the perspective of “domestic circulation as the mainstay, international circulation as an enabler, and the smooth and efficient operation of both circulations”. By using spatio-temporal statistical methods, it analyzes the dynamic evolution and driving forces of the efficiency of the integrated development of the domestic and international circulations in urban agglomerations of the Yangtze River Economic Belt. The results show that the efficiency of the integrated development of the domestic and international circulations in urban agglomerations of the Yangtze River Economic Belt is at a relatively low level, with significant spatial differences. The development quality of the domestic circulation is obviously better than that of the international circulation. From 2010 to 2020, the coupling and coordination degree of economic dual circulation among urban agglomerations and among their constituent provinces and municipalities remains low, and the regional heterogeneity is obvious. The efficiency of the integrated development of the domestic and international circulations in urban agglomerations of the Yangtze River Economic Belt shows a step-by-step decreasing difference from the east to the middle and then to the west. The overall growth trend is positive, but the spatial polarization trend is severe. This research is of practical significance for grasping the law of the integrated development of the domestic and international circulations in the Yangtze River Economic Belt, promoting the formation of new growth poles in underdeveloped areas, and thus accelerating the construction of the new development paradigm.