Purpose: The present study aimed to examine the mediation role of loneliness in the relationship between perceived social support and depressive symptoms among university students in Portugal. The study also investigated the moderation role of age on the mediation model. Design/methodology/approach: Survey data sample consisted of 755 participants (aged 18-55 years) attending university in Lisbon, Portugal, from February through May 2023. Participants completed the UCLA Loneliness Scale, Multidimensional Scale of Perceived Social Support (MSPSS), Depression, Anxiety, Stress Scale. The SPSS Program with PROCESS macro (Model 4 and Model 8) was used to test the hypotheses regarding the mediation and the moderated mediation effects. Findings: The bootstrap result for indirect effect loneliness ([beta] = -0.083, p < 0.0001) was significant, indicating that loneliness mediated the relationship between perceived social support and depressive symptoms. Moreover, the interaction term (perceived social support x age) had a significant positive effect on the direct negative association between perceived social support and depressive symptoms (B = 0.0312; p < 0.05), showing that age moderated the direct relationship between the aforementioned variables. Importantly, the results showed that age moderated the indirect association (via loneliness) between perceived social support and depressive symptoms. Originality/value: This research advances our understanding of loneliness among university students of different age ranges while providing empirical data on the effect of loneliness in the relation of social support and depressive symptoms. Moreover, the study delves on possible strategies to combat the expression of loneliness and further depressive symptoms.