E-STEM (Environmental, Science, Technology, Engineering and Mathematics) refers to the integration environmental education into STEM education and can have important role on students' understandings and engineering design process about environmental issues such as plant growth, acid rains, pollution, sustainable agriculture etc. since it engages students in real-world environmental problem-solving that integrates science, technology, engineering, and math. In this manner, the aim of this study was to investigate the effect of E-STEM Education on fifth grade students' perceptions and their engineering design process about environmental issues. To reach this aim, a one-group pre- and post-test model was used. The research group of study is five 5th grade students at private school, Istanbul, Turkey. The data was collected with open-ended questions, focus group interview and researchers' observation notes. In data analysis, students' responses to open-ended questions were analyzed with content analysis and classified in terms of adequacy. Transcribed discussions from focus group interview and researchers' observation notes were assessed based on Engineering Design Process Framework. As a result of the study, students' perceptions and engineering design process about environmental issues improved through E-STEM Education.