Online interactions have emerged as a dominant exchange mode for companies and customers. Cultivating online relationships—defined as relational exchanges that are mediated by Internet-based channels—presents firms with challenges and opportunities. In lockstep with exponential advancements in computing technology, a rich and ever-evolving toolbox is available to relationship marketers to manage customer relationships online, in settings including e-commerce, social media, online communities, mobile, big data, artificial intelligence, and augmented reality. To advance academic knowledge and guide managerial decision making, this study offers a comprehensive analysis of online relationship marketing in terms of its conceptual foundations, evolution in business practice, and empirical insights from academic research. The authors propose an evolving theory of online relationship marketing, characterizing online relationships as uniquely seamless, networked, omnichannel, personalized, and anthropomorphized. Based on these five essential features, six tenets and 11 corresponding propositions parsimoniously predict the performance effects of the manifold online relationship marketing strategies.