Performance of the National Treasury is of critical importance since it affects service delivery of other public entities. Low performance levels posted by the National Treasury has drawn a lot of attention from the citizens and corporate stakeholders especially with the ever increasing public debt, challenge in policy formulation and the challenge of adapting to information technology dynamics. Through Employee engagement, both public and private organisations attempt to improve organisational non-financial performance. Employee engagement includes practices such as job design, communication, leadership and rewards. Although many organizations have made efforts to enhance organizational performance, the measures of organizational performance they have adopted have not been appropriate especially for public and non-profit making organizations, for instance; relying on financial performance measures. The general objective of this study therefore was; to establish the effects of employee engagement and non- financial performance of National Treasury in Nairobi, Kenya. The findings of this study would be of great benefit to the National Treasury, Kenya and to all organization in the public. The study was guided by the following specific objectives; to assess the effects of job design, leadership, communication and rewards on organizational performance in the public sector in Kenya. This study was anchored on the Work Adjustment Theory, Stakeholder Theory, Social Exchange Theory and Vroom’s Expectancy Theory. This study adopted a descriptive research design. The target population was made up of 876 staff of the national treasury and using stratified sampling technique, a sample of 269 was included in the study. Primary data was collected using a questionnaire. Analysis of data was done using descriptive analysis and inferential analysis. A positive and significant effect was established between job design, leadership, communication and rewards on performance. The study concludes that the job design specifies the contents and procedures of performing the task in the organization. Hence, it helps in designing organizational structure. Leadership is vital for both in building the strength and power of the organization and in helping to manage relationships and resources. When managers and senior staff are good communicators themselves, they can expect to bring out each individual’s best skills and increase performance and through reward systems the employee will feel more motivated to work harder by having a reward system in place the employee will feel more committed to their work and their productivity will increase. The study recommends that through reward systems the employee will feel more motivated to work harder by having a reward system in place the employee will feel more committed to their work and their productivity will increase. The organization should the organization should establish its leadership standards and define the areas where managers need to excel in terms of directing the work of others. The organizational management should create a job description that eliminates ambiguity by clarifying the responsibilities and expectations for each member of your organization. The management of the organization magnify employee recognition by publicizing employee accomplishments across multiple forums such as company newsletters, dashboards and in team meetings.