The aim of this study was to review the literature on what constitutes happiness across cultures and countries to advance scholarly knowledge on the happiness construct. A systematic review was conducted to examine the determinants of happiness in samples across cultures and countries. Five different databases, including APA PsycNet, EBSCO-Academic, EBSCO-Business, Project MUSE, and Google Scholar, grey literature, and in-text references from relevant review articles were used. A total of 155 articles were included in the review, encompassing studies from over 100 countries and 44 cultures. Myriad determinants of happiness were found that were placed into three broad categories labeled Health, Hope, and Harmony. The predominant happiness determinants were mental, emotional, and physical well-being, a purposeful holistic work–life balance, nurturing social relationships, caring for self and others, and being in harmony with one’s culture, traditions, community, religion, and environment. This study engendered an “Integrated Model of the Determinants of Happiness” to provide a universally applicable conceptualization of the happiness construct. By examining studies on determinants of happiness across the globe in the past 90 years, this review uncovered that happiness constitutes multiple determinants that fall under three major categories: ‘Health’, ‘Hope’, and ‘Harmony.’