Integrating local knowledge into the STEM (science, technology, engineering, and mathematics) learning process through PjBL (project-based learning) can help learners develop themselves as a whole that is oriented toward adequate science literacy skills. The study aims to examine the effectiveness of STEM-PjBL learning using BAJARDI (digital IPA teaching materials) to improve the science literacy of learners. This is a quasi-experimental study with two groups of control experiments. Experimental classes use BAJARDI in the STEM-PjBL learning process, while control classes use conventional learning models. The research sample consisted of 120 students from a Class IV elementary school. The sample technique used is a random sampling. Scientific literacy test instruments are used to collect data. The validity of an instrument is determined by the Aiken index, while the reliability of the instrument is measured by the alpha Cronbach coefficient. Independent-Samples T The information is analyzed using test and quantitative descriptive statistics. This research identified a substantial difference in the average value of science literacy between the experimental and control groups (sig =. 00). The results of this research indicate that STEM-PjBL learning with BAJARDI is extremely effective in improving student science literacy. Keywords: STEM, Project based learning, local knowledge, scientific literacy.