Sustainable building practices are essential for reducing the environmental impact of the construction industry, with green building rating systems (GBRSs) like Green Star NZ playing a key role. This research examines the limitations of the Green Star NZ rating system from the client’s perspective, aiming to propose measures to enhance its adoption within NZ’s construction industry. Through a systematic literature review (SLR) and semi-structured interviews with industry professionals and client representatives, the study identified critical barriers to adoption, including the complexity of the certification process, high initial costs, a skills gap within the industry, and resistance to change among clients. Despite these challenges, the Green Star NZ system is valued for standardising sustainable practices and its adaptability to local conditions. To overcome the barriers, the research suggests strategies such as streamlining the certification process, offering financial incentives, improving client education and industry training, and showcasing successful projects. Implementing these strategies could lead to broader adoption of the Green Star NZ rating system, thereby advancing sustainable building practices in NZ. The findings offer actionable insights for policymakers, industry stakeholders, and clients, paving the way for more effective green building certification.