This study examined the impact of improved rice varieties adoption on rice productivity and farming households’ welfare in Nigeria using a cross sectional data of 481 rice farmers drawn from three states to represent the major rice producing ecologies (Irrigated, upland and lowland) in Nigeria. Access to seed was found to be one of the significant determinants of adoption. Poverty incidence was also higher among the non-adopters than the adopters. This study also adopted the counterfactual outcomes framework of modern evaluation theory to provide a consistent estimate of the impact. Specifically, the LATE which uses the system of instrumental variable method was adopted to assess the impact of improved rice varieties adoption on rice productivity and total household expenditure (Proxy for welfare). The results showed a significant positive impact of on rice productivity (358.89kg/ha) and total households’ expenditure ( N32890.82) This suggests that adoption of improved rice varieties significantly generate an improvement in farming household living standard. Hence, efforts should be intensified to ensure farmers have access to adequate quality improved rice seed at the right time. All programs, strategies and policies that could lead to increase in improved rice adoption should be intensified in order to achieve the much desired poverty reduction and generate an improvement in rural farming households’ welfare in Nigeria.