Psychological wellbeing is an important factor for university students in order to achieve their goals and reach their potentials while they are in a significant transition period. Being mindful and being solution-focused increases university students' psychological wellbeing. This study aims to examine the mediating role of solution-focused thinking in the relationship between mindfulness and psychological wellbeing of university students. Mindful Attention Awareness Scale, The Flourishing Scale, Solution-focused Inventory, and a demographic information questionnaire were used to collect data from 543 (356 female, 184 male, and 3 unanswered) undergraduate students at a state university in Turkey. The results showed that mindfulness (present moment attention and awareness) predicted psychological wellbeing, goal orientation and resource activation dimensions of solution-focused thinking positively and problem disengagement dimension of solution-focused thinking negatively. Similarly, psychological wellbeing was predicted by goal orientation and resource activation positively and problem disengagement negatively. The mediation analyses revealed that mindfulness affected psychological wellbeing indirectly through solution-focused thinking. This study starts a discussion about negative predictive roles of problem disengagement on psychological wellbeing. Thus, different predictive effects and mediating roles of solution-focused thinking's sub-dimensions were discussed.