As one of the provinces with the largest number of national forest cities, all prefecture-level cities in Guangdong Province have joined the campaigns of building forest cities. Mastering the spatial and temporal variations of ecological environment quality (EEQ) in Guangdong Province is conducive to the benign interaction and coordinated development of urban construction and ecosystem. We used the water benefit-based ecological index (WBEI) to achieve rapid monitoring of EEQ in Guangdong Province, utilized the standard deviation ellipse and gravity center migration, Theil-Sen Median trend method and Mann-Kendall test to explore the spatial distribution disparities and trends, and analyzed the coupling coordination between EEQ and urbanization. The results showed that the WBEI derived from the normalized difference vegetation index could better reflect vegetation coverage in Guangdong Province, and objectively evaluate the EEQ of watersheds and urban vegetation zones. The EEQ in the northern inland area was generally better than that in the southern coastal area, and it was more concentrated in the southwest-northeast direction. The gravity center position displayed a sequential movement from southwest to northeast and then back to southwest. Most prefecture-level cities remained stable or improved in EEQ, while the improved and degraded types were distributed in various regions of the province. The coupling coordination degree between EEQ and urbanization in southern Guangdong Province exceeded that of the northern region, with the coupling coordination degree being constantly improving. The Pearl River Delta Forest City Cluster emerged as a region characterized by high levels of coupling coordination, with a good radiation driving effect in promoting the coordination of EEQ and urban construction. This study could provide a method reference for EEQ evaluation within multi-watershed forest cities.