This study was conducted to examine the efficiency of socioscientific issues-based instruction on the development of the scientific literacy levels (scientific content knowledge, science-technology-society interactions, and the nature of science) of pre-service science teachers and their conceptual perception of socioscientific issues in science teacher education. In this mixed method research study, in which convergent parallel design (QUAN+QUAL) was utilized, both quantitative and qualitative research phases were administered concurrently. The study group included a total of 82 pre-service science teachers (40 experimental and 42 control) currently enrolled as third-year students in the Department of Elementary School Science Education. A basic science and technology literacy scale was used as the quantitative data collection tool, whereas pre-service science teachers' diaries, a focus group interview, and in-class observations were used as qualitative data collection tools. At the end of the study, it was concluded that the practices of socioscientific issues-based instruction quantitatively improved the scientific literacy level of pre-service science teachers in the experimental group. It was also found that the improvement in overall scientific literacy levels was due to an improvement in the nature of science area of scientific literacy in particular. Parallel to this finding, the pre-service science teachers made explanations in relation to the nature of science area based on the results of the qualitative phase. These explanations were made using the "changeability" sub-theme under the theme of conceptual perception of "socioscientific issues". Thus, based on both the quantitative and qualitative findings of the study, it can be argued that socioscientific issues-based instruction can influence the improvement of pre-service science teachers' perceptions of the nature of science. Finally, it was found that the pre-service science teachers in the experimental group had improved levels of conceptual perception of socioscientific issues. Therefore, it is believed that this approach, which places an emphasis on the social dimension of science, can contribute positively to the professional training of pre-service science teachers.