Abstract: Organic agriculture is one of the most popular sustainable agricultural production methods and has become an important measure for the realization of green, high-quality agriculture and rural revitalization in China. Farmers are rational decision-makers, and whether the adoption of organic agriculture can increase farmer incomes is critical to the promotion of organic agriculture and the achievement of green agricultural development in China. However, there is no consensus regarding this challenge. To provide evidence supporting the promotion of organic agriculture, the effects of organic agricultural adoption on farmer incomes must be empirically evaluated. We selected Aksu, Kashgar, Bazhou, and Hotan in southern Xinjiang as the study area, where agroecological conditions, climate, and level of economic development are relatively homogeneous. Considering the selectivity bias introduced by unobservable variables, we applied the endogenous transformation regression (ESR) model to scientifically test the income-increasing effect of organic agricultural adoption by farmers. In addition, we used group regression to explore the heterogeneity of the income-increasing effect of organic agricultural adoption, based on the field survey data of 451 jujube farmers in Xinjiang. The empirical results showed that the adoption of organic agriculture can significantly increase the income of jujube farmers. If jujube farmers, who adopted organic agriculture, do not adopt organic agriculture, their income would decrease by 48.65%. If jujube farmers, who not adopted organic agriculture, adopt organic agriculture, their income would increase by 53.57%. Moreover, significant heterogeneity was evident in the income-increasing effect of organic agriculture among jujube farmers. For those farmers with higher education levels and larger farms who participated in contract agriculture within national certified organic product demonstration zones, the income-increasing effect of organic agriculture adoption was more significant. Accordingly, to increase farmer incomes through the organic jujube industry, the promotion of organic farming must be strengthened. Considering the heterogeneity of income-increasing effects, the government could encourage jujube farmers to expand their cropped area through land transfer and other means, increase the participation rate in contract agriculture, and extend certified organic product demonstration zones, thus improving the income-increasing effects of adopting organic agriculture among jujube farmers. Although the analysis of data from farmers in Xinjiang can provide a reference for green, sustainable development of agriculture in ecologically fragile oasis areas, the generalizability of its conclusions to other regions is somewhat limited. Next, we intend to expand the scope of the research within the pioneer organic agriculture farming areas and conduct follow-up research with the sample farmers to attain a more in-depth and systematic understanding of the dynamic effect on farmer incomes following adoption of organic agriculture.