The dual structure of urban and rural areas has existed for a long time. As a special link connecting urban and rural areas, the multi-dimensional integration of migrant workers in cities has a profound impact on comprehensively deepening rural reform and promoting the integrated development of urban and rural areas. From the perspective of the multi-dimensional integration of migrant workers, this paper adopts data from the China Migrants Dynamic Survey (CMDS) and identifies the causal effect of the public rental housing policy on the integrated development of urban and rural areas through the fuzzy regression discontinuity design. The findings are as follows: First, the public rental housing policy significantly alleviates the multi-dimensional living difficulties of migrant workers and plays a positive role in promoting the integrated development of urban and rural areas. Second, the “income compensation effect” directly brought about by monetary subsidies and the “demand creation effect” indirectly generated by in-kind subsidies jointly promote the integrated development of urban and rural areas. Specifically, monetary subsidies directly increase the disposable income of migrant workers, and in-kind subsidies indirectly drive potential consumer demand by improving living conditions. Third, vulnerable groups such as those with a lower level of education, those with accompanying children, and those working in non-state-owned enterprises face greater difficulties in integration, which makes the guarantee effect of the public rental housing policy more pronounced. Fourth, the public rental housing policy also alleviates the household registration place difficulties of migrant workers through the intergenerational feedback mechanism. That is to say, the welfare effect of the public rental housing policy will feed back to the families in the household registration place through means such as financial assistance and resource transmission. The evaluation and feedback results of the effect of the public rental housing policy will help to further understand the welfare effect of housing security systems, improve the mechanism for the integrated development of urban and rural areas, and promote the high-quality development of Chinese path to modernization.