Background: This paper begins with the premise that ethics and diversity, equity, and inclusion (DEI) overlap in engineering. Yet, the topics of ethics and DEI often inhabit different scholarly spaces in engineering education, thus creating a divide between these topics in engineering education research, teaching, and practice. Purpose: We investigate the research question, "How are ethics and DEI explicitly connected in peer-reviewed literature in engineering education and closely related fields?" Design: We used systematic review procedures to synthesize intersections between ethics and DEI in engineering education scholarly literature. We extracted literature from engineering and engineering education databases and used thematic analysis to identify ethics/DEI connections. Results: We identified three primary themes (each with three sub-themes): (1) lenses that serve to connect ethics and DEI (social, justice-oriented, professional), (2) roots that inform how ethics and DEI connect in engineering (individual demographics, disciplinary cultures, institutional cultures); and (3) engagement strategies for promoting ethics and DEI connections in engineering (affinity toward ethics/DEI content, understanding diverse stakeholders, working in diverse teams). Conclusions: There is a critical mass of engineering education scholars explicitly exploring connections between ethics and DEI in engineering. Based on this review, potential benefits of integrating ethics and DEI in engineering include cultivating a socially just world and shifting engineering culture to be more inclusive and equitable, thus accounting for the needs and values of students and faculty from diverse backgrounds.