Adult obesity has remained a key health concern globally. Theory-based social marketing interventions are considered effective for improving dietary and physical activity (PA) behaviours. However, their application in universities is not yet established. This review aimed to identify social marketing strategies targeting healthy eating and/or PA behaviours of young adult university students and outline the intervention effectiveness. Literature search, screening, and data extraction followed the Joanna Briggs Institute (JBI) methodology for scoping reviews. PubMed/Medline and Scopus databases were searched for intervention and exploratory studies published between January 1, 2000, and September 20, 2023. Twelve articles were selected based on the eligibility criteria. Although different in study design, all studies reported improved healthy eating-related outcomes, while three showed improved PA-related outcomes. One study incorporated all six of the social marketing benchmarks, but the majority identified two. Most studies focused on behavioural objective, formative research, and marketing mix in their intervention design. Four studies incorporated behaviour change theories in development of the social marketing campaigns. Social marketing using social media could be a significant approach for improving healthy eating and PA in young adult university students when behavioural change theories and all social marketing benchmarks are adopted. More generalizable longer-term investigation into the effectiveness of this approach in university young adults is needed to tackle adult obesity related health issues.