Countries in sub-Saharan Africa (SSA) rely heavily on imported rice from Asia that is of superior quality relative to local rice. The objectives of this study are to assess the impacts of the adoption of improved milling technologies and the associated structural transformation of the rice value chain from 2011 to 2019 using the original census of the rice millers in the Mwea Irrigation Scheme in Kenya. Our empirical analysis uses the doubly robust method and the endogenous switching model, which collectively reveal that the adopters of improved milling machines successfully improved the quality of local milled rice to allow it to compete with imported rice, thereby increasing the amount of domestic rice sold to supermarkets as well as to urban traders and consumers. It is also found through probit regression that a few educated, entrepreneurial rice millers operating in rice milling clusters adopted large-scale improved milling machines that included destoning ability, importing them from China around 2010. Later, smaller-sized improved machines were also introduced and more widely adopted in the rice milling clusters. In contrast, the many other millers that did not adopt improved machines were forced to down-size their business or exit the industry. These results imply that adopting improved milling technologies, including destoners, is critical to improving the competitiveness of SSA’s domestic rice against imported rice.