The main purpose of this study was to explore how proactiveness influences the performance of healthcare units in Nairobi County, Kenya. The study specifically sought to determine how the five indicators of proactiveness namely: barriers and accident prevention, safety management, disease prevention, hazard analysis and availability of tool sets influence the performance of healthcare units in Nairobi County. To compete effectively, healthcare units must constantly improve their performance by reducing maternal mortality, reducing child mortality and increasing the number of referrals to the healthcare unit. The study adopted a survey research design and the target population were the healthcare units in Nairobi County. The target population was healthcare units in Nairobi, comprising County Hospitals, Health Centres and Health Clinics totalling to 71 and the sample size was 49. Data was collected using questionnaires and analysed using SPSS and Microsoft Excel. Inferential data analysis was carried out by the use of factor and correlation analysis. Regression models were fitted and hypothesis testing carried out using multiple regression analysis and standard F and t tests. The findings of this study from multiple regression analysis indicated that proactiveness positively influenced performance of healthcare units in Nairobi County. The study results led to the conclusion that proactiveness improves the performance of Healthcare units in Nairobi County. The study recommends that healthcare units should focus on practicing barriers and accident prevention, carrying out hazard analysis, carrying out disease prevention, carrying out safety management and using tool sets during service to clients since their practice is necessary to ensure improved performance.