Teachers encounter the challenge of how to provide students adequate awareness of science-related careers. Therefore, innovative teaching material for promoting science-related careers needs to be designed. Educational innovations can be successful if teachers experience ownership and agency towards the designed teaching material. In this case study, a multi-professional group of two science teachers, a researcher, and a dentist co-designed instruction including a career presentation and relevant information about field-specific education and skills needed by a professional in that field. We refer to this as career-related instruction. The designed learning unit includes a scenario, inquiries and career-related activities. Teachers' perceptions about co-designing and implementing the learning unit in science education are examined as well as students' perceptions about the scenario. Data consists of teacher interviews and discussions and student questionnaires. A content analysis reveals the teachers' high ownership and agency in co-designing the instruction, which was relevant, interesting and informative for students. It was easy for teachers to implement the learning unit even though they were not involved in every phase of the design process. We conclude that by strengthening teachers' ownership and agency through multi-professional co-designing, relevant and interesting career-related instruction can be designed and implemented.