Scientific literacy is a crucial competency for the 21st century, empowering citizens to make critical decisions and to be more informed about global challenges. This study explored the impact of authentic research experiences on mathematics pre-service teachers' (PST) conceptual understandings of Nature of Science (NOS), Scientific Inquiry (NOSI), and their science researcher identities. Acknowledging that holding informed views of NOS/NOSI and science identity, more specifically, science researcher identity, are crucial constructs to foster and develop scientifically literate citizens, this research addressed the gap in understanding the relationship between these two constructs when PSTs participate in an authentic research experience. The present study used a qualitative, exploratory, multi-case study design to explore the impact of an authentic research experience on three mathematics pre-service teachers. Data were collected pre- and post-experience, including the Science Identity Survey, the Views of Nature of Science (VNOS) questionnaire, and the Nature of Scientific Inquiry (VASI/VOSI) questionnaire. Responses were analyzed to create participant profiles and identify cross-case patterns. Additional data were gathered through semi-structured interviews, reflective journals, and research logs, which were coded and thematically analyzed to build a deeper understanding of participants’ experiences. Findings demonstrated that participating in an authentic research experience, along with reflective components, supported the simultaneous development of science researcher identity and NOS/NOSI understanding. Participants demonstrated shifts toward developing a deeper understanding of scientific practices and the idea that scientific inquiry is interdisciplinary. Additionally, this study revealed a process of identity renegotiation, as the mathematics PST’s expanded their identities beyond mathematics to include science identities, therefore blurring disciplinary boundaries. This shift was accompanied by increased recognition of the interconnectedness between science and mathematics, supporting more integrated conceptions of STEM. These findings suggest that authentic research experience can serve as a promising mechanism for developing both epistemological understandings and identities, both of which are essential for supporting STEM integration in K-12 education. However, further research is needed to examine this expansion of single-discipline identities to STEM identities and how that translates into classroom practice. Implications from this study can further inform not only teacher preparation programs and professional development initiatives but also promote best practices for other researchers interested in engaging in this type of research.