In today's world, where young adults face increasing psychological and social challenges, understanding the factors that influence loneliness has become more critical than ever. This study examines whether perceived self-efficacy mediates the relationship between parental acceptance and loneliness in university students. The study population consists of undergraduate students studying at universities affiliated with the Council of Higher Education in Türkiye. Data were collected with demographic information form created by the researchers, UCLA Loneliness Scale, Adult Parental Acceptance-Rejection Scale, Coping Self-Efficacy Scale. Independent samples t-test and one-way analysis of variance were used for comparisons between groups, and Pearson's correlation analysis and mediation analysis were used to analyze the relationships between variables. According to the results, the level of acceptance perceived by male students from their mothers was higher than that of female students. There is a significant negative relationship exists between loneliness levels and parental acceptance of university students. It was found that parental acceptance scores significantly predicted loneliness and coping self-efficacy scores. This study shows that self-efficacy has a partial mediating role in the relationship between parental acceptance and loneliness and that self-efficacy may create resistance against negative emotions. Identifying this relationship and potential mediating effects at an early stage is important for strengthening the family environment and promoting healthy child development. This study will contribute to the literature with new findings to identify protective factors and develop psychosocial interventions for young adults struggling with loneliness.