This pressing issue requires immediate attention and action. Education, particularly STEM education, is one of the key areas that can contribute to addressing this issue. STEM education is an alternative learning strategy that can enhance students' problem-solving and decision-making skills in relation to the challenges posed by the need for clean water. However, the extent to which these two skills are interconnected remains unclear. Therefore, this study was conducted to measure the effect of STEM on problem-solving and decision-making skills, as well as to explore the relationship between these two variables. This study employed a quasi-experimental design with a sample of 54 students, focusing on the topic of water pollution and its solutions. Based on the MANCOVA test, the results showed significant effects of STEM education. In the experimental group, the p-value for problem-solving ability was 0.001, and for decision-making ability, it was 0.000, indicating a substantial impact of STEM education on both skills. Furthermore, a strong correlation between problem-solving and decision-making skills was observed, particularly in the context of water pollution and its solutions. The findings suggest that STEM education effectively supports students in exploring complex issues and equipping them to meet the demands of 21st-century skills, especially those related to environmental challenges.