Despite a widespread understanding of whole life costing within the Tanzanian building construction industry, practical implementation remains limited. A significant hindrance to the adoption of this approach is the absence of dependable cost data. To address the challenge, this paper introduces a robust cost data management framework designed to facilitate the integration of whole life costing practices in the industry. The framework, evaluated by 34 building construction professionals in Tanzania through a mixed-method research approach embracing a quantitative survey and qualitative interviews with 11 participants, is recognised for its clarity, comprehensiveness, and relevance to the industry. It provides a strategic roadmap for leveraging technology to establish a readily accessible and efficient system for managing cost data. Despite positive feedback, challenges to the proposed framework include reluctance to change, technological limitations, and financial constraints. Nevertheless, the potential benefits of the framework, such as the provision of reliable cost data, expedited access to information, and overall improvement in cost data management, are acknowledged. This research underscores the critical role of overcoming the lack of dependable cost data as a pivotal step towards promoting the adoption of whole life costing practices in the Tanzanian building construction sector, emphasising the need for a technologically driven approach to enhance the accessibility and reliability of cost data.