Expanding the manufacturing sector is a major part of the government‟s Vision 2030 economic development plan to transform Kenya into a middle-income country by growing the manufacturing to account for 20% of GDP by 2030 which is nearly twice today‟s level, at 10.6%. Addressing some outstanding constraints in the manufacturing sector is the panacea of achieving the goals. The main objective of this study is to evaluate the effects of TQM practices on performance of manufacturing firms in Nyeri County. The specific objectives of this study are to assess how top management commitment, customer focus, continuous improvement and employee training affect the performance of the manufacturing firms in Nyeri County. The literature review identifies what other researchers have done in the area of TQM practices on performance of firms globally and locally. The study sought to determine the relationship between the dependent and independent variables. The study was based on the Deming‟s theory, resource-based theory and the institutional theory. The manufacturing firms under study were twelve in Nyeri County and emphasis was placed on the top management. The staff comprises of managers in finance, marketing, production, procurement, research and development, quality assurance, human resource with a total of 75 persons considered. The study adopted a census owing to the small number of respondents involved. Questionnaires were used for data collection. Data analysis entails descriptive statistics which encompass frequencies and percentages. Inferential statistics by use of the SPSS program entailing the chi-square to test causal relations and regression was done. The study found out that continuous improvement had a positive influence on performance of manufacturing firms in Nyeri County. Employee training had a positive influence on performance. Top management commitment had a positive influence on performance. Customer focus positively influenced performance. The study concludes that manufacturing organizations were kept neat and clean at all times. Production equipment was maintained well according to maintenance plans. Manufacturing organization used Statistical Process Control (SPC) programs for process control. Selection and recruitment process in their organization was effective (in terms of the objectivity and „right man for the right job‟). Communication was open and continues in three directions: up, down and across. Senior executive insisted on accuracy and reliability of all information and communications within the organization