According to the World Health Organization well-being has been defined as one outcome parameter indicating successful recovery from diseases. One disease causing significant psychosocial problems and distress is Gambling Disorder that is being characterized as a poorly controlled excessive engagement in gambling activities. While there are several studies investigating treatment-effects in patients with Gambling Disorder, the role of well-being as a complementary treatment outcome has not been studied so far. In our research project it was aimed to fill this gap by gathering data on changes of eudaimonic dimensions of well-being from 76 patients with Gambling Disorder before and 1 year after receiving inpatient treatment. At both waves (pretreatment and follow-up) we collected data regarding well-being (Ryff Scales of Well-being), psychopathological symptoms (SCL-9), and diagnostic criteria for Gambling Disorder (Lie/Bet-Questionnaire). We found some dimensions of well-being changing 1 year after treatment and that patients recovered from Gambling Disorder displayed significant increments in Autonomy and Environmental Mastery. In contrast, patients still meeting criteria for Gambling Disorder displayed well-being increments only in Environmental Mastery and decreases in Personal Growth and Positive Relations with Others. Only changes in Environmental Mastery and Self-Acceptance were significantly associated with decreases in psychosocial distress indicating that well-being is an additional indicator for treatment outcome. It was also intended to identify factors predicting increments in well-being. However, no relationships were found regarding demographics, clinical variables, or treatment parameters. It is proposed to acknowledge well-being as an additional indicator for treatment effects and suggested to implement therapeutic strategies for an early enhancement of well-being.