Purpose: Scientific literacy plays an important role in catalyzing science learning in the 21st century. Unfortunately, previous evidence revealed that students' scientific literacy tends to be unsatisfactory. This study investigated the effect of ethnoscience-themed picture books embedded in context-based learning (EthCBL) on students' scientific literacy. Methods: In this quasi-experimental research, 58 (35 girls and 23 boys) fifth-grade students in a public elementary school in Indonesia were selected using purposive sampling. Twenty-nine students (19 girls and 10 boys) were assigned as an experimental group and 29 students (16 girls and 13 boys) were assigned as a control group. The Scientific Literacy Test (SLT) was employed to measure students' scientific literacy in prior and subsequent interventions. Data were analyzed using independent and paired t-tests at the 0.05 significance level. Findings: The results showed that EthCBL was more effective in promoting the scientific literacy of fifth-graders than traditional teaching. After treatment, the experimental group showed higher posttest scores in all sub-scales of scientific literacy compared to the control group. Implications for Research and Practice: In this study, EthCBL was integrated with the surrounding culture that allows students to learn more and participate actively which made their scientific literacy increase. Therefore, it is recommended that teachers apply EthCBL to improve the scientific literacy of elementary school students to a satisfactory level.