Learning about careers and the world of work supports the increased engagement and achievement of young people in secondary school, enabling them to make better choices about future pathways and work. While trained guidance counsellors have an important role to play in supporting this learning, most students have limited access to such counsellors, and some have none at all. Secondary school teachers are central to students' lives and have the capacity to play an important role in building their career knowledge, but there is little research on their current role in career guidance or what it might ideally look like. We conducted a Delphi study with 64 international career guidance experts on what an enhanced role in careers provision for secondary teachers might look like, and what would need to be in place to make such a role successful. There was strong support for an enhanced role, noting that such a role would require increased attention to careers in initial teacher education, appropriate professional learning and curriculum materials, a whole-school approach to careers led by a career leader/guidance counsellor with careers expertise, and changes to systemic priorities and accountabilities. We discuss implications for policy, practice and research.