This research investigates students' decision-making and collaborative skills within the science teaching and learning process through integrated Science, Technology, Engineering, and Mathematics (STEM) education. Although collaborative skills and effective decisionmaking are vital in the 21st century, many students still lack proficiency in these areas. To address this issue, a structured methodology has been adopted to enhance the development of these skills in science education. The study involves designing and validating an instructional unit for integrated STEM (IUI-STEM) education, which is implemented directly in the classroom. Sixty-four seventh-grade students from two different schools participated in the research. Improvements in decision-making and collaborative skills were analyzed using the Wilcoxon rank-sum test. A valid IUI-STEM education unit was developed specifically for this case study. The findings indicate that learning through integrated STEM education, facilitated by the IUI-STEM unit, significantly improves decision-making skills in science (p < 0.001; Z = -4.644; d = 1.421). Additionally, there is a notable improvement in students' collaborative skills before and after the integrated STEM education (p < 0.001; Z = -5.102; d = 1.85). By nurturing collaboration and decision-making skills through integrated STEM education, students will be better prepared for success in future academic pursuits and careers that demand strong teamwork and problem-solving abilities.