The integrated development of agriculture and tourism is an effective driving force to boost farmers’ income. We utilize a quasi-natural experiment design to test how such integrated development promotes the comprehensive rural revitalization. By adopting a panel dataset of 72 counties within Guangxi province from 2005 to 2020 and a PSM-DID method, we attempt to explore the effect of the integrated development of agriculture and tourism on farmers’ income growth. The empirical results support our hypothesis that the integrated development of agriculture and tourism can effectively promote farmers’ income growth and its regional heterogeneity with respect to tourism resource endowment and economic development level. We further discuss the transmission mechanism of the integrated development of agriculture and tourism and reveal that the agricultural technology level and agricultural production efficiency have mediating effects on improving farmers’ income growth. However, a masking effect exists between the integrated development of agriculture and tourism and the level of non-agricultural employment. The possible reason is that industrial and commercial capital investment has crowded out the welfare originally belonging to the wage income and only allowed farmers to obtain the one-time land rent income.