An important part of STEM education is students' acquisition of knowledge, skills, and abilities needed for career success, all of which emerge from a combination of classroom and co-curricular activities. Work-related experiential activities (WREAs) offer the opportunity for students to engage in experiential activities before degree completion, and these experiences provide students with an important way to refine their skills that facilitate career success. Generally, prior research confirms the benefits of work-related experiential activities in students' transition to the workforce, but more evidence is needed to examine the contribution of WREA participation in the development of career competencies. This paper focuses on engineering and computer science students' perceptions of skills related to career competence that were enhanced during WREA participation. Sixty-three percent of the students surveyed in spring 2021 and spring 2022 at five institutions in one U.S. state said they completed one or more WREAs during their baccalaureate studies. With only a few significant differences by students' gender, race/ethnicity, or financial aid status, student responses indicated high value in developing skills related to career competence, and in particular, professionalism and communication. Student perceptions are detailed, and implications for STEM research and education are discussed.