Malaysians have expressed their commitment to energy efficiency. To reflect this commitment, certain buildings have started to adopt the Green Building Index (GBI) to support the government's sustainability agenda. However, there is a strong argument that the lack of stakeholder awareness and satisfaction might become an ongoing challenge. This study aims to investigate the perceptions of stakeholders regarding GBI-certified office buildings. Specifically, this study focuses on awareness, communication, satisfaction, and energy-related behaviours. The Theory of Planned Behaviour (TPB) was used to underpin the study that links attitudes, perceived control, and behavioural intentions. A descriptive survey with an embedded qualitative component approach is employed, collecting data through a questionnaire and supplemented with qualitative data from open-ended questions. The questionnaire is designed to measure awareness of certification, communication effectiveness, perceived energy use, and satisfaction with building operations. In contrast, the open-ended responses are designed to provide deeper insights into challenges and suggestions on the GBI. A total of 90 structure surveys were collected from the occupants of the building. The results reveal that there are a moderate awareness of GBI status, limited communication from management, and a desire for greater involvement in energy-saving initiatives. However, satisfaction with energy efficiency efforts was mixed as many cited the Heating, Ventilation, and Air Conditioning (HVAC) as a key concern. The study contributes to the growing literature on behavioural aspects of green buildings, highlighting the importance of communication and participatory engagement in operationalising sustainability. Practical implications are offered for building managers to enhance communication strategies and stakeholder engagement in energy initiatives.