Teachers play an essential role in teaching sustainable development to students. Consequently, understanding the challenges that hamper effective instruction is crucial. This study explored the challenges preparatory and secondary school teachers face in Qatar’s public and private schools when teaching Education for Sustainable Development (ESD) and Global Citizenship Education (GCED). The study utilized an adapted version of UNESCO’s global survey to investigate these challenges and shed light on the obstacles that impede effective instruction in these essential domains. Teachers’ (N = 981) challenges were assessed according to curricular, cultural, and environmental challenges associated with teaching sustainability. The study results indicated that more than half of public and private school teachers faced moderate to significant challenges when teaching ESD and/or GCED themes. Sustainable Consumption and Production was perceived as the most challenging teaching theme, with the least curriculum coverage. Results indicated that private school teachers report more significant challenges in teaching and assessing ESD/GCED themes than public school teachers across the four sustainability themes. Detailed discussion regarding these findings is provided. This article contributes to the wider academic conversation by examining the practical challenges teachers face in Qatar as they implement ESD and GCED.