Customers and other stakeholders are increasingly concerned about the environmental and social impacts of economic activity, which includes the marketing of products and services. While traditional marketing is often associated with the one-sided stimulation of needs that go far beyond actual needs, with the continuous acquisition of new customers through attractively priced and heavily advertised offers that may disregard social or ecological compatibility, sustainability marketing aims to fulfill a fundamentally new role here. This role involves generating sustainable value for current and future stakeholders by balancing ecological, social, and economic concerns. Creating and exchanging products or services that offer sustainable value requires forming and shaping relationships with various stakeholders. This chapter addresses the fundamentals of relationship-oriented sustainability marketing. It shows how the concept has evolved from so-called modern marketing, relationship marketing, and sustainability marketing with the latter’s various development lines such as ethical marketing or ecological (eco-) marketing. Relationship-oriented sustainability marketing is characterized by drawing on its fundamental principles and theoretical underpinnings, target groups, and objectives.