The purpose of this study was to develop a paradigmatic model of entrepreneurial orientation in knowledge-based firms with an emphasis on sustainable marketing strategies and to identify the causal, contextual, intervening, strategic, and consequential factors associated with this phenomenon. This study was applied in terms of purpose and employed a qualitative grounded theory methodology. The study population consisted of experts and managers of knowledge-based firms holding master’s or doctoral degrees with at least ten years of managerial experience. Purposeful sampling was used, and interviews continued until theoretical saturation was achieved. A total of 15 semi-structured interviews were conducted, and the data were analyzed through open, axial, and selective coding procedures. During the analytical process, initial concepts were extracted and categorized into main and subcategories, leading to the development of the final paradigmatic model. The findings indicated that entrepreneurial orientation based on sustainable marketing strategies in knowledge-based firms is influenced by three categories of causal conditions, including strategic and managerial drivers, technological capabilities and infrastructures, and environmental pressures and requirements. Contextual conditions such as human capital structure, technological infrastructures, networking capacity, and organizational culture also played a significant role in shaping this phenomenon. Intervening conditions, including resource limitations, environmental dynamism, and competitive pressures, affected the intensity and direction of the process. The main organizational strategies included the development of sustainable innovation, implementation of responsible marketing, and reinforcement of entrepreneurial and networking capabilities. The outcomes of these strategies were reflected in improved organizational performance, sustainable competitive advantage, enhanced social capital, organizational learning, and innovation capacity development. The results demonstrated that entrepreneurial orientation based on sustainable marketing is a multidimensional and strategic approach in knowledge-based firms that emerges through the interaction of managerial, technological, and environmental factors. This orientation can facilitate sustainable growth, continuous innovation, enhanced competitiveness, and shared value creation for organizations and society. Adopting this model enables knowledge-based firms to move toward sustainable development and value-creating entrepreneurship.