Organisations have become interested in using integral management systems to increase their sustainable value. Although global integration models address sustainability in organisations, these models present shortcomings and limitations and do not describe how to achieve the integration of sustainability. This paper proposes an Activity-Based Sustainability (ABS) integration model that complements other models from an inside-out perspective. Its assessment follows a procedure similar to that proposed by the Activity-Based Costing (ABC) model of cost accounting. The model assigns impacts from activities in the value chain of a process to the objects of impact (products, services, clients, or markets) that must be managed in terms of sustainability. The main limitations of the ABS model are the need to identify and describe processes, to locate every activity that constitutes the value chain, and to quantify the impacts of these activities. The ABS model is presented as an alternative to link sustainable management accounting and sustainable communication, as well as sustainable management control and sustainability assessment. It connects these sustainable elements through the bilateral identification of the linkages among skills, processes, and practices. It also links these aspects with the contribution to sustainable development and the development of competitive advantages.