There is a paucity of research on the links between gay dating apps usage and body dissatisfaction and disordered eating, especially for muscularity dissatisfaction and muscularity-oriented disordered eating in non-Western contexts. Thus, this study aimed to evaluate the associations between gay dating apps usage, body image inflexibility, body dissatisfaction, and disordered eating with the inclusion of both body fat and muscularity dissatisfaction and both thinness–and muscularity–oriented disordered eating in a sample of Chinese young gay men. A total of 247 Chinese young gay men (mean age: 21.92 ± 2.74 years) were recruited. Gay dating apps usage, body fat dissatisfaction, muscularity dissatisfaction, body image inflexibility, and thinness–and muscularity-oriented disordered eating were evaluated. Pearson correlation and mediation analyses were conducted. Gay dating apps usage was positively correlated with body fat dissatisfaction (r = .20, p = .002), muscularity dissatisfaction (r = .17, p = .006), thinness-oriented disordered eating (r = .21, p < .001), and muscularity-oriented disordered eating (r = .29, p < .001), and these relationships could be mediated by body image inflexibility. Findings support technologically-informed prevention and intervention strategies for eating and body image disturbances in gay men in the Chinese context.