Background: Intensive care nursing requires continuous surveillance, complex procedures, rapid recognition of deterioration, infection prevention, accurate documentation, communication, and timely intervention. Contemporary literature has emphasized the need for clearly defined and context-specific nursing-sensitive indicators that can represent nursing processes and outcomes more comprehensively. Aim: This study aimed to develop proposed Key Nursing Performance Indicators (KNPIs) for intensive care units at the National Heart Institute. Design: A methodological design was utilized. Setting: The study was conducted at the National Heart Institute, Cairo, Egypt. Sample: A convenient sample of 70 nurses working in selected intensive care units was included. Three observations were conducted for each nurse, resulting in 210 observations. Tools: Data were collected using a personal and work-related data form, a nursing staff perception regarding key nursing performance indicators, an observational KPI checklist, and an expert opinionnaire for face and content validity of the proposed indicators. Results: The largest proportion of nurses were aged 30 to less than 45 years (45.7%), female (77.1%), married (82.9%), and holders of a technical nursing diploma (58.6%). Most nurses had substantial clinical experience; however, 100% reported no previous training in quality performance and management. Several clinical process indicators improved markedly across repeated observations. DVT prophylaxis increased from 17.1% to 100% (χ2=21.32, p<0.001), daily oral care with chlorhexidine increased from 34.3% to 100% (χ2=11.67, p=0.001), arterial-line fluid-balance monitoring increased from 17.1% to 100% (χ2=8.82, p=0.003), and the proposed Key Nursing Performance Indicators (KNPIs) for Intensive Care Units (ICUs). The findings revealed an exceptionally high level of agreement among the 15 experts, with an overall agreement rate of 100% for all items and no reported disagreement. Conclusion: The observational findings demonstrated variable levels of compliance across different nursing-care domains. Ventilator-bundle compliance improved across observations, with statistically significant improvements in DVT prophylaxis and daily oral care. Finally, the expert opinionnaire demonstrated 100% overall agreement regarding the proposed Key Nursing Performance Indicators, supporting their relevance, applicability, clarity, understandability, and representation of the study dimensions. Recommendations: adopt developed a standardized Key Nursing Performance Indicator system for ICU nursing practice and Integrate the proposed KNPIs into the hospital's quality-management system and ensure that they are clearly communicated to all ICU nursing staff..