The present study investigates the potential of urban mobility projects to contribute to the achievement of sustainability goals. It focuses in particular on transformations of the transport system that integrate public space design and the characteristics of the built environment. The work is part of a more extensive research project which aims to formulate a comprehensive methodology to assist local authorities in the definition of sustainable mobility initiatives since the early stages of the planning process. This paper presents the first part of the proposed methodology: the analytical-design model—composed of dimensions, criteria, operational requirements, and project attentions—and its application methods. Specifically, the key dimensions represent the domains of spatial organization and human activities—interconnected and interacting—in which integrated land use and mobility projects primarily act. The operational model has been designed to serve as a framework for project development and to provide a qualitative assessment of sustainability. The model is tested through a case study: the regeneration of the San Simplicio neighbourhood in Olbia, Italy. The purpose of this test is twofold: firstly, to validate the criteria and requirements that articulate the analytical framework with particular attention to the dimension “Public spaces and characteristics of the built environment”; secondly, to demonstrate the model’s applicability and effectiveness in revealing the project’s contribution to sustainability in terms of quality, achieved benefits, and limitations. The study highlights the model’s potential as a flexible and integrative tool for supporting sustainability in urban mobility planning and its capacity to guide project development through different levels of detail (requirements and project attentions).