Despite the urgency of protecting the environment, unsustainable apparel consumption continues to damage it. We identified some of the most important consumer concerns (i.e., affordability, social desirability, environment protection) from the literature that influence consumers’ sustainable apparel purchase intentions and proposed a conceptual model grounded in the Elaboration Likelihood Model to test the efficacy of user-centric advertisements in encouraging purchase intentions for sustainable apparel. We conducted a between-subject experiment with female millennials in the U.S. (n = 344). Analyzing the data through ANCOVA, MANCOVA, and structural equation modeling, we evinced that (i) irrespective of involvement with environmental issues, user-centric advertisements could be centrally (thoughtfully) processed when they incorporate consumers’ concerns for affordability, social desirability, and environment protection; (ii) the central processing of user-centric advertisements mediates the relationship between advertisement modalities (textual and textual with visual) and affective response toward sustainable apparel; (iii) the processing of user-centric advertisements evokes favorable affective responses (e.g., desire) and minimizes unfavorable affective responses (e.g., boredom) toward sustainable apparel; and (iv) favorable and unfavorable affective responses positively and negatively influence purchase intentions for sustainable apparel, respectively. Based on our findings, we recommend that marketers should communicate how sustainable apparel meets consumers’ concerns of affordability, social desirability, and environment protection in a holistic manner instead of using pro-environmental cues only.