Reclaimed water reuse plays a critical role in alleviating water scarcity while demonstrating potential to mitigate water pollution and reduce carbon emissions. However, comprehensive assessments of its resource and environmental benefits remain insufficient. This study takes 45 cities in China's northern arid-semiarid regions as examples. Based on evaluating the spatiotemporal evolution of their blue water footprint (BWF), grey water footprint (GWF), and carbon emissions, it analyzes the resource and environmental benefits of reclaimed water reuse. We find that from 2013 to 2022, the BWF in northern China's arid-semiarid regions increased by 1.65 Gm3. During this period, 77.8 % of the cities experienced significant or severe blue water scarcity. Concurrently, the volume of reclaimed water reuse increased by 0.93 Gm3, and its contribution to reducing the region's BWF rose from 0.3 % to 1.7 %. Furthermore, both GWF and water pollution level significantly declined, with 32 cities achieving over 5 % GWF reduction (relative to 2013 baselines) through reclaimed water reuse by 2022. Carbon emissions exhibited a sustained growth trend throughout the study period, concurrent with a decline in the carbon sequestration rate from 0.21 to 0.14; nevertheless, reclaimed water reuse also contributed to a reduction in the study region's carbon emissions, with its contribution rising from 0.016 %o in 2013 to 0.050 %o by 2022. Notably, this impact displayed stark regional disparities. Additionally, despite the significant positive impacts of reclaimed water reuse on reducing regional BWF, GWF, and carbon emissions, challenges persist including limited adoption rates, environmental pollution and health risks, and spatial trade-offs and synergies with carbon reduction. This study's revelation of the resource and environmental benefits of reclaimed water reuse could provide scientific guidance for scaling up implementation while addressing SDG 6 (Clean Water) and SDG 13 (Climate Action) challenges in water-scarce cities.