Scientific achievements concerning the direct relation between personality traits and positive orientation among patients with multiple sclerosis do not explain the role of potential mediators. In fact, some researchers argue that the traits–positivity association is much more complex than it seems to be. For this reason, we made an attempt to analyze the indirect relationship between the above-mentioned variables, including meaning in life as a mediator. In total, 618 patients with MS took part in the study. The NEO Five-Factor Inventory, the Positive Orientation Scale, and the Meaning in Life Questionnaire were used. The results showed that positive orientation/the presence of meaning/searching for meaning correlated positively with extraversion, openness to experience, agreeableness, and conscientiousness, and were negatively associated with neuroticism. Moreover, meaning in life in both its dimensions acted as a mediator in 9 of 10 models. It can be assumed that a propensity to establish interpersonal relationships (extraversion), use active imagination (openness), inspire confidence among others (agreeableness), and take responsibility (conscientiousness) can have an impact on someone’s positive attitude toward oneself and the surrounding world (positive orientation) when people have meaning in life and when they are seeking it.