The purpose of this study was to examine the relationship between socioemotional competencies (SEC) and happiness of emerging adults with the moderating role of mindfulness and social media engagement (SME). Over the past decade, psychologists and neuroscientists have begun to pay more attention to the relationship between SEC and individuals' wellbeing. However, there remains a gap in the comprehensive exploration of SEC concerning happiness, particularly in light of mindfulness practices and SME, both of which could have substantial impacts on individuals' happiness. This study included two universities from two different countries (Nepal and the United States). Study 1 included 70 participants (Mage = 25.0 years, SD = 6.3 years), approximately 43% of women (n = 30), and Study 2 included 154 participants (Mage = 22.5 years, SD = 5.7 years), approximately 81% of women (n = 125). In the data analysis process, hierarchical regression and moderation analyses were used. Based on the analyses, SEC and mindfulness had a statistically significant relation in increasing happiness in Study 2; however, mindfulness had a strong association with happiness throughout the two studies. Neither study found the moderating role of mindfulness on happiness. In Study 1, SME moderated the relationship between SEC and happiness. This showed that higher SME with higher SEC was significantly associated with happiness in Study 1. However, SME did not moderate the relationship between SEC and happiness in Study 2. The overall study results indicated that researchers, educators, and developmental psychologists should continue to investigate how SEC, mindfulness, SME, and happiness may be related.