The Social Cognitive Career Theory (SCCT), one of the highly researched career theories, suggested that outcomes expectance and self-efficacy are crucial factors in the career selection process. The result of career outcomes expectancy (COE) and career decision-making self-efficacy (CDSE) may be pivotal in an individual’s shunning or being more inspired in their career behaviour. Both factors together are important in career decision-making. The aim of this study was to investigate the association among COE and CDSE of science, technology, engineering and mathematics (STEM) students at a South African university. The article is based on a quantitative study conducted among a sample of 322 STEM students, of which 203 responses were received. The career outcomes expectancy scale (COES) and career decision self-efficacy scale (CDSES) were used in the collection of data. Data were analysed with the IBM SPSS version 26 software and descriptive statistics, Pearson’s correlation, linear regression and multivariate analytical tools were engaged. Findings show that age and race significantly associated with CDSE. Additionally, COE was found to have a statistically significant relationship with CDSE and that CDSE positively predicted COE. The environment of upbringing was also found to be influential in participants’ CDSE and COE. In line with extant literature, the discussion of the findings is made to proffer recommendations that have implications for practice, policy and further studies.