This study investigates the integration of EthnoSTEAM into mathematics education, focusing on the importance of incorporating students' cultural contexts to enhance their learning experiences. Traditional mathematics education often fails to account for the cultural backgrounds of students, hindering their ability to connect mathematical concepts to real-life situations. EthnoSTEAM--a multidisciplinary approach that combines ethnographic and cultural perspectives with STEAM fields--seeks to bridge this gap by infusing cultural diversity into the curriculum. The study employs a qualitative research approach, structured into three stages. Initially, a literature review was conducted to identify gaps in existing research on EthnoSTEAM-oriented mathematics education. This informed the design of professional development training for teachers on the EthnoSTEAM approach. In the second stage, teachers collaborated to co-design lesson plans that integrated students' cultural contexts, guided by both theoretical frameworks and literature review insights. These lesson plans were implemented in classrooms during the third stage, with student performance, participation, and feedback closely observed, and teacher experiences documented through interviews and diaries. The research adopted a qualitative approach, utilizing a design-based research model. Data were collected through various forms, subjected to document analysis, and analyzed using descriptive and content analysis methods. Preliminary findings suggest that EthnoSTEAM-oriented lesson plans significantly enhance student engagement and motivation, making mathematics more relevant and meaningful. In this context, a framework for the application of the EthnoSTEAM approach to mathematics courses is presented. However, further comprehensive analysis and long-term monitoring are necessary to fully understand the impact on student achievement and to guide broader implementation strategies. [This paper was published in: "EJER Congress 2024 International Eurasian Educational Research Congress Conference Proceedings," edited by Senel Poyrazli, Ani Publishing, 2024, pp. 188-194.]