Groundnut (Arachis hypogea L.) is a major annual oilseed crop and its economic and nutritive quality makes the crop a beneficial enterprise for rural farmers in Ndhiwa Sub-County. Researchers have recommended adoption of technology and increased contact with extension agents as one way of increasing production but productivity remains low. Crop productivity or yield is a function of environment, plant, management and socio economic factors that interact at optimum levels to give maximum yields. The study focused on farmer characteristics which are part of socio-economic factors using the ex-post facto research design. The objective was to determine the influence of farmer characteristics on the production of groundnuts in Ndhiwa Sub County, Kenya. Purposive, multistage and simple random sampling was used in the study. Data on famer characteristics was obtained from 323 farmers out of the population of 21,820 farmers involved in groundnut production during the 2014 main cropping season. Document analysis was used to collate and analyze secondary data. Cobb-Douglas production function model and multiple regression analysis were used to study the behavior and effects of independent variables on the dependent variable and test hypotheses. The results of the study showed that majority of the farmers were in households that were male headed with an average of seven persons. The household heads were middle aged, experienced in groundnut farming and had low levels of formal education. Age, gender of head of household, household size, level of formal education and experience in farming all had a positive relationship with groundnut production. However, only gender and experience in farming were significant at p <0.05 level of significance. Based on the findings the study recommended that interventions that target female headed households and improvement of farmers’ traditional knowledge on production should be put in place to improve production.