Following the promulgation of the new constitution of Kenya in 2010, several functions previously done by the central government were devolved to the counties. County government of Nakuru has various human resource functions that have been devolved from the central government of Kenya; these include devolved recruitment and selection, devolved rewards and benefits, and devolved training and development functions. This change in and of itself is expected to affect employee performance. The researcher sought to establish the extent to which these devolved HR functions have affected employee performance given that no information was available to this end. The specific objectives were to determine the effects of devolved recruitment and selection, devolved rewards and benefits, and devolved training and development functions on employee performance. A survey was carried out within Nakuru County Government Headquarters which has a workforce of 301 permanent employees as at January 2016. The study adapted a descriptive research design. Stratified random sampling technique was employed. Sample size of 93 respondents was determined using Nassiuma’s formula. A questionnaire was used to collect data and results were presented in tables and figures. Both descriptive and inferential statistics were used to analyze the data with the aid of Statistical Package for Social Sciences(SPSS). The findings showed that devolved recruitment and selection ( r = 0.441, α = 0.000),devolved rewards and benefit ( r = 0.331, α = 0.001 ) and devolved training and development (r = 0.374, α = 0.000) were positively correlated to employee performance. Multiple linear regression analysis showed that devolved recruitment and selection (β= 0.177, p value=0.006),devolved rewards and benefit ( β = -0.031, p value=0.748) and devolved training and development (β = 0.131, p-value=0.164) were all significant (p value=0.000) when combined under multiple regression model. The study further found that all the independent variables; devolved recruitment and selection, devolved rewards and benefit and devolved training and development can explain the variation of employee performance by up to 19% when combined under multiple regression model.