The extent to which brain training is beneficial for both cognition and emotional well-being is explored in a naturalistic study design capturing users of the online brain training program MyBrainSolutions over a 2.5-year period. A total of 2,752 users trained to a minimum required level and completed a validated assessment battery of cognitive and emotional states before and after training, which compared their performance to a large database of healthy norms. Both the games and the assessment were designed to tap both cognitive (thinking) and emotional domains, with emotional functioning broken out into nonconscious reactions (emotion), conscious experience (feeling), and conscious regulation (self-regulation). The relationships between game play and improvement in assessment scores were established using linear regression models. Games within the domains of thinking, emotion, feeling, and self-regulation were found to have beneficial effects in improving measured scores on the assessment within these same domains. The most significant benefits were found for games training positivity to improve scores within anxiety, stress, and depression (feeling scores). In addition, training in self-regulation was found to be beneficial in terms of improved memory, attention, and executive function and reduction in anxiety, stress, and depression levels. While follow-up studies are needed to further elucidate these findings, initial results from a snapshot of naturalistic use indicate a beneficial effect of brain training on cognitive skills and emotional well-being. Furthermore, results suggest a synergistic effect of cognitive and emotional training.