The purpose of this article is to examine the effects of STEM (Science, technology, engineering, and mathematics) education practices carried out at the primary school level in Turkey on various learning outcomes. The systematic review method was employed to accomplish this purpose. This study examined whether 30 comparisons from publications found through database searches and meeting the inclusion criteria revealed a significant difference. The analyses conducted led to a finding that STEM education used in primary schools had favorable and statistically significant effects on attitude towards STEM (f=6), academic achievement in a science course (f=5), 21st-century skills (f=2), interest in careers in STEM fields (f=2), scientific creativity (f=2), basic skills (f=2), entrepreneurial skills (f=1), social skill (f=1), reflections on the nature of science (f=1), STEM perception (f=1), and Scratch achievement (f=1). On the other hand, the study's findings showed that these practices did not produce a statistically significant difference in academic achievement in mathematics courses (f=1) and reflective thinking skills toward problem-solving (f=1). Additionally, the study's findings showed that 2 practices created a statistically significant difference in the positive direction on problem solving skills, and 2 practices did not create a statistically significant difference.