Healthcare systems play an important role in addressing climate change through the adoption of sustainable organisational practices. However, the successful implementation of climate action initiatives often depends on internal organisational factors such as institutional culture and employee engagement. This study examined organizational culture as a predictor of climate action implementation within NHS Trusts in Greater Manchester, United Kingdom. A quantitative cross-sectional correlational design was employed. Data were collected from 200 healthcare professionals, including doctors, nurses, allied health professionals, and administrative staff working in NHS Trusts. Participants completed the Organizational Culture Assessment Instrument (OCAI) and the Implementation Climate Scale (ICS) to assess perceptions of organisational culture and the extent to which climate-related initiatives were implemented within their institutions. Data were analysed using descriptive statistics, Pearson correlation analysis, and multiple regression analysis in SPSS. The results revealed a significant positive relationship between organizational culture and climate action implementation (r = .46, p < .001). Regression analysis further indicated that organizational culture significantly predicted climate action implementation, accounting for approximately 21% of the variance in sustainability practices within NHS Trusts. These findings suggest that supportive organisational cultures characterised by collaboration, innovation, and leadership support may enhance the implementation of sustainability initiatives within healthcare organisations. The study highlights the importance of organisational and behavioural factors in achieving the objectives of the NHS Net Zero strategy. Implications for healthcare management, organisational development, and sustainability policy within the NHS are discussed.