Emerging sustainability concerns have long-term implications for business organisations. Despite these concerns, the methodologies and frameworks that companies employ to integrate sustainability practices remain indeterminate in the literature. The absence of a unified sustainability management framework, coupled with limited empirical studies, renders the integration of sustainability practices within business models both impractical and uncertain for organisations. This study seeks to bridge this gap by synthesising two domains of literature: sustainability measurement (encompassing social, environmental, and economic sustainability (SEES) and sustainability business models, to delineate factors that facilitate sustainability implementation. These factors are analysed through the lens of institutional theory across 22 UK listed companies, aiming to identify the institutional factors that shape such practices within organisations. The empirical investigation employed a qualitative analysis of semi-structured interviews with sustainability directors, managers, and professionals from these companies. Data analysis was conducted using the Gioia qualitative methodology via NVivo software. The study presents the development of a four-stage 'Integrated Sustainability Management Framework (ISMF)', based on the reconceptualised PDCA cycle of strategy and objective setting, integrated operations, evaluation and monitoring, and reviews and outcomes. The findings indicate that the implementation of sustainability in UK listed companies follows a well-defined process, significantly influenced by the companies' specific institutional contexts, including governmental mandates, voluntary initiatives, and globally recognised standards and frameworks (e.g., GRI, UNSDGs, ISO, FTSE). Consequently, this study proposes four distinct and heterogeneous sustainability implementation pathways: material relevance, existing management systems, international frameworks and reporting standards, and in-house developed pathways to complement the ISMF and cater to individual companies' specific contexts. This study makes three significant contributions. Firstly, it contributes to institutional theory by complementing the existing body of research on sustainability management frameworks by highlighting the influence of institutional factors in delineating previously unexamined pathways through which companies integrate sustainability practices into their business models. Secondly, it contributes empirically to the literature and demonstrates significant practice-based implications for managing organisational sustainability issues. Lastly, the ISMF serves as a practical tool enabling companies to identify the critical enablers and processes for embedding SEES practices within their organisations.