The increasing urbanization of the built environment has bolstered the need of promoting sustainable practices and Building Information Modelling (BIM) initiative in building and construction projects. However, there has not been a unified adoption and implementation of BIM initiative and sustainability in most countries and the built environment as a whole – most notably within the sub-Saharan region of Africa due to several factors. Moreover, based on the extant literature, the existing green rating tools have been found to be inadequate to fully address the greenness and evaluate the sustainability performance of buildings. Hence, these generate several hindrances to the current drive for a holistic implementation of sustainability practices and innovative technologies such as BIM in the construction industry. Therefore, this research study aims to develop a green-BIM assessment model and cloud-based sustainability decision support system for evaluating buildings' compliance to sustainability principles with a view to integrating smart sustainable practices in building construction and management, improving operational efficiency, and enhancing the overall implementation of sustainable development in the built environment. The scope of study mainly focuses on developing countries located in the sub-Saharan region of Africa – using Nigeria, the largest economy in the region as a case study – with practical applications to other regions. The following research objectives was set out in fulfilling the study’s aim: (1) To identify and assess the inherent benefits, barriers, and critical success factors (drivers) associated with integrating BIM and sustainability principles in building projects. (2) To establish the relative weightings of the key sustainability indicators, sustainability attributes, and sub-attributes for buildings. (3) To develop a sustainability evaluation index for buildings using the Generalized Choquet Fuzzy Integral method. (4) To develop a cloud-based sustainability decision support system (C-SDSS) for buildings. (5) To develop a conceptual Green-BIM assessment framework as a tool for the evaluation of sustainability performance of buildings. Objective #1 was achieved via an in-depth desktop review of extant literature, pilot and Delphi surveys, empirical questionnaire surveys, as well as the use of several statistical analysis tools such as descriptive and inferential statistical tools, factor analysis, and fuzzy synthesis evaluation method. According to the desktop literature review, a total of 36 benefits, 38 barriers and 30 critical success factors were identified. Fourteen (14) experts from eight countries participated in the Delphi survey while 220 respondents from 21 countries were involved in the international questionnaire survey. Meanwhile, the base inputs for the data to achieve Objectives (#2 - #4) consisted of 189 diversified sets of experts in Nigeria with requisite experience in the built environment. A holistic review of green building technical notes and guidelines, existing green building rating systems, and relevant journal articles was undertaken to fulfil Objectives (#2 - #4); and augmented by industry experts’ inputs which facilitated the development of the Building Sustainability Assessment Method (BSAM) scheme. The BSAM scheme green rating system has been designed for developing countries in the sub-Saharan region of Africa. The proposed BSAM scheme is a more unified green rating tool that adequately considers the environmental, economic, and social pillars of sustainable development unlike the existing green rating tools such as LEED, BREEAM, BEAM Plus, Green Mark, etc. which focus solely on the environmental sustainability with little or no consideration of the other two sustainability pillars. Objective #3 was actualized by employing the Generalized Choquet Fuzzy Integral (GCFI) method to establish the weightings of the 8 key sustainability indicators, 32 sustainability attributes, and 136 sustainability sub-attributes of the BSAM scheme. Data collected from industry experts form the base inputs for the impacts of various sustainability criteria based on the local variations. The GCFI approach is regarded as a more practical and robust weighting method for non-additive, dependent, and interactive criteria. Consequently, the Building Sustainability Evaluation Index (BSEI) and a six-grade certification system were developed to evaluate the sustainability performance of building projects. The key sustainability criteria with the highest weighting based on the GCFI analysis include sustainability construction practices, transportation, and energy criteria. To ease the adoption and implementation of the proposed BSAM scheme, BSEI, and the BSAM certification system for use in the built environment, a Cloud-Based Sustainability Decision Support System (C-SDSS) was established to achieve Objective #4. PHP and Jscript, being high-level programming languages, as well as the MySQL relational database along with other web-based tools and systems were used to code, design, and deploy the C-SDSS platform. BIM models, and relevant data from four real-life building projects based in Nigeria were used during the validation exercise to demonstrate the usefulness of the developed C-SDDS and the BSAM scheme in practice for the built environment. The validation exercise was augmented with validation questionnaire surveys with industry experts. Finally, a conceptual green-BIM assessment (GBA) framework was developed as an effective tool for the evaluation of the sustainability performance of buildings using a cloud-based system (Objective #5). The proposed GBA framework comprised of six main components is intended to provide comprehensive guidelines and algorithms that can facilitate the full and optimal integration of BIM and green building rating systems (e.g. the proposed BSAM scheme) in the assessment of the sustainability performance of buildings. The developed GBA framework was validated using expert questionnaire surveys as well. The findings of the study have generated salient and significant contributions both from the theoretical and practical (industry) standpoints. Moreover, they have provided valuable insights, effective strategies, and recommendations that have addressed the limitations of the integration of the concepts of BIM and sustainability practices in the built environment. Overall, the research deliverables would be crucial in implementing Green-BIM both locally (in Nigeria and other sub-Saharan countries), and internationally.