The study sought to determine the impact of adoption and use of mobile phone technology on the performance of micro and small enterprises in Kisii municipality, Kenya. The owner's' perception on mobile phone adoption, purpose, sources, factors and perceived effects were studied. The study targeted owners of MSEs in Kisii Municipality. A cross sectional survey research design aimed at identifying MSE owners' perception on the adoption and use of mobile phone technology was used. Stratified sampling was used to identify the MSEs and simple random sampling techniques used to select the respondents and questionnaires placed to collect the data. A questionnaire was used to collect data and a split-half method of estimating reliability used with the aim of assessing the reliability and validity of the research instrument through the expert advice of the supervisors and faculty. The study sample comprised four hundred (400) owners of MSEs out of a population of three thousand five hundred and twenty eight (3528). Once the data had been collected, quantitative data was analyzed using descriptive statistics such as mean, distributions in percentages and frequency counts. Qualitative data was recorded from field data, transcribed and reported in themes and sub themes. Multiple regression analysis was also utilized to assess the relationship among the independent and dependent variables. The study showed among other findings, that there is an impact on adoption and use of mobile phone technology on the performance of micro and small enterprises.