Applying the sociocultural theory and the objectification theory, this experiment examined the indirect effects of inspirational Instagram images (i.e., fitspiration and thinspiration) on young women’s sexual attitudes. A post-test only between-subjects design with three experimental conditions (i.e., fitspiration, thinspiration, and control images) was conducted with female college students ( N = 221). The results supported the sociocultural theory, revealing that viewing inspirational Instagram images led to higher appearance comparison and greater body dissatisfaction, respectively, which, in turn, predicted lower sexual self-efficacy and greater sexual self-consciousness. Testing a new theoretical model combining the sociocultural theory components and self-objectification reported a significant causal mediating chain of appearance comparison, self-objectification, and body dissatisfaction, respectively, in the relationship between viewing inspirational Instagram images and sexual attitudes (i.e., lower sexual self-efficacy and greater sexual self-consciousness). The indirect effect sizes of fitspiration were larger than those of thinspiration. Implications and limitations are discussed.