Dong Nai Province, located in southeastern Vietnam, has experienced rapid industrial and agricultural development, accompanied by increasing pressure on groundwater resources. Excessive groundwater extraction raises concerns regarding water quality, agricultural sustainability, and public health. This study assessed groundwater contamination by nitrate, selected heavy metals, and bacterial indicators across the province. A total of 55 groundwater samples were analyzed for nitrate, arsenic (As), cadmium (Cd), mercury (Hg), lead (Pb), total coliforms, and Escherichia coli (E. coli). The mean nitrate concentration was 18.02 mg/L, with the highest levels observed in Bien Hoa City. Lead contamination was widespread, exceeding drinking-water standards at several locations, while elevated As and Cd concentrations were detected only at a limited number of sites. Bacterial contamination, indicated by total coliforms and E. coli, was detected in multiple districts, particularly in Long Khanh. Although the results primarily indicate associations rather than direct causal relationships, they highlight potential risks to groundwater used for domestic supply and agricultural irrigation. The findings provide evidence to support improved groundwater monitoring, agricultural water management, and policy development aimed at safeguarding rural livelihoods and sustainable agricultural development in Dong Nai Province.