Agricultural commercialization has a potential to increase farming households’ income and standard of living. This study assessed the degree of rice commercialization and the determinants of commercialization of rice farmers in Ahero Irrigation Scheme, Kenya. Stratified and probability proportionate to size sampling were used to select 221 rice farmers. A Household Commercialization Index (HCI) was computed to estimate the degree of commercialization and then modeled as a function of explanatory variables. Informed by the Chow test, three regressions were estimated; male, female and the whole sample. The HCI were 0.77, 0.79 and 0.78 for male, female and whole sample respectively. Household size, off-farm income generating activities, household income, rice price and pesticides usage were significant determinants of rice commercialization. The recommended policy options are to advice and train farmers on pesticides use and the government to have a planned exit from agriculture by introducing attractive off-farm income generating activities.