The numerous industrial parks in China present crucial water issues along with their essential role in improving economic development. Facilitating sustainable water stewardship in industrial parks is pragmatically essential for water-efficient industry. This study proposes an integrated method to synthesize a water stewardship index (WSI) from the perspective of water utilization, wastewater emission, and water reuse. The WSI is then employed for 219 national-level industrial parks (NIPs), which account for about 12% of China's gross domestic product. Water use, efficiency, and conservation potential can be quantified by employing the index. The key findings are as follows. Freshwater consumption (5,476 Mt/a) and wastewater emission (2,559 Mt/a) accounted for 4.2% and 13% of the total from secondary industry in China respectively. The average water consumption intensity of the NIPs was 1,462 t/mCNY, only one-third of the national average (4,586 t/mCNY). However, the discrepancy in the intensity among NIPs is remarkable: the top 50% of NIPs have an average of 443.4 t/mCNY, which is 17% of the average of the bottom 50% (2,605 t/mCNY). Improving the water recycling rate, reducing conventional pollutant emissions, and developing unconventional water resources, such as reclaimed water, rainwater, and desalinated water, are promising ways to improve the WSI. After accessing the benefits of facilitating water stewardship by benchmarking eco-industrial parks, the average WSI improvement could reach 14.2%; the water conservation and GHG emission mitigation potentials associated could reach 4,164 Mt/a and 4.11 Mt/CO₂-eq, respectively, accounting for 57% and 44% of the baseline scenario. Five key measures are proposed to improve the WSI and overall environmental efficiency of the NIPs.