We aimed to determine differences in mental health outcomes for the adult population depending on their personal experience during the first months of the war in Ukraine. The study involved 1,257 respondents (32.3% male and 67.7% female, aged 18–61+ years). We used the Brief Resilience Scale, the Professional Hardiness Questionnaire, the General Self-Efficacy Scale, the Posttraumatic Growth Inventory—Expanded, the Short Screening Scale for DSM– IV post-traumatic stress disorder (PTSD), and the Giessen Subjective Complaints List. The obtained data showed high pressure of physical complaints and high levels of PTSD symptoms in adult Ukrainians. We found that positive mental health outcomes were significantly higher in adults with ‘Active’ personal experience during the first months of the war in Ukraine, which was shown by their significantly higher levels of four positive mental health indicators (resilience, general level of professional hardiness, self-efficacy and level of post-experience change). Negative mental health outcomes were significantly higher in adults with ‘Passive’ experience, which was shown by their significantly higher levels of two negative indicators (pressure of physical complaints and manifestations of PTSD symptoms). Our findings indicate a high need for psychological support and assistance for the Ukrainian population and show the direction of possible interventions.