This research study sought to establish the effect of working capital investment on company profitability in Kenya , a case study of selected NSE listed non-financial firms. The study was guided by the following four objectives to evaluate the effect of growing sales volume on company profitability, to assess the impact of operational cost on company profitability, to investigate the influence of fixed assets turnover on company profitability and to determine the relationship between working capital investment and company profitability. The rate of working capital investments was measured using Cash Conversion Cycle, Average accounts payable, Inventory turnover and Average collection period .A descriptive research design was adopted in this study and a sample of 18 firms was selected... purposively from the total population of all the 42 firms non-financial firms listed at Nairobi Securities Exchange. Secondary data for the 18 firms were obtained from the audited financial statements for the period between 2013 -2017. The Statistical Package for the Social Studies (SPSS) was used to analyse both descriptive and quantitative using regression and correlation models to determine the relationship between the dependent and independent variables. The study established that cash conversion cycle and average payment periods has great effect on firms profitability represented by 46 % and 47 % respectively while inventory turnover period and average collection period have slight influence on firms profitability this is represented by 10% and 18% respectively .the study concluded that it is necessary for the finance managers to manage account payables and sales turnover because they help a lot in establishing the amount of profits a firm can get.