Although there is increasing empirical evidence of the negative impact of childhood maltreatment on adult mental health and well-being, little is known about the underlying factors that mitigate the link between psychological maltreatment and psychological adjustment. A critical step is to examine these mechanisms to develop prevention and intervention strategies to decrease the adverse impacts of child maltreatment on psychological adjustment and well-being among young adults. The presented study aimed to explore the association between childhood psychological maltreatment and young adults’ psychological adjustment through aversion to happiness, optimism, and pessimism. The sample of this study comprised 511 college students. Participants included 64% female, with ranging in age between 18 and 39 years (
M
= 21.36,
SD
= 2.55). Findings from the study indicated that aversion to happiness was a significant mediator in the association of psychological maltreatment with pessimism, optimism, and psychological adjustment. Further, optimism and pessimism mitigated the link of both aversion to happiness and psychological maltreatment with psychological adjustment. The findings indicate that optimism-based strategies are key to fostering psychological adjustment and could help to reduce the negative impacts of aversion to happiness and child maltreatment on young adults’ adjustment and wellbeing.