In the policy arena of the rapid development of China’s digital village, understanding how internet use enhances the happiness of forest farmers’ families holds theoretical and practical significance for promoting the protection of the ecological environment and the sustainable development of forests. This study utilizes survey data from 2023 on forest farmers in ecologically fragile ethnic areas in China. Based on sustainability, a five-dimensional evaluation index system for the happiness of forest farmers’ families has been constructed. First, the CRITIC-TOPSIS model is employed to calculate the happiness scores of forest farming households. Subsequently, the Tobit model and the mediation effect model are applied to examine and analyze the influencing factors and mechanisms of internet usage on the happiness of forest farmers’ families. The study finds that, first, an increase of one unit in terms of internet use is associated with a 0.031-unit increase in the happiness of forest farmers’ families, and that education, social perception, and policy perception all have a positive effect on the happiness of forest farmers’ families. Second, the mechanism of action suggests that internet use significantly increases forest farmers’ families’ happiness through subjective class identity. Third, further heterogeneity analyses revealed that internet use contributed to the happiness of forest farmers’ families in the male group, the low human capital group, and the group with an ecological forest ranger in the family. Therefore, it is necessary to strengthen the construction of digital rural infrastructure and develop new models such as digital forestry; cultivate and introduce specialized digital talents in rural areas and enhance the digital literacy of forestry farmers; and assist forestry farmers in establishing class identity concepts and social values conducive to the sustainable development of forests and implement ecological values in production practices, thereby improving the happiness of forest farmers’ families.