Luxury fashion brands have shifted their advertising focus from traditional magazines to social media platforms, marking a transition from ad-context congruence to incongruence. However, its impact on luxury perception remains underexplored. This study investigates how ad-context congruence and processing fluency influence consumers' luxury perception, with brand familiarity as the moderator. Using an experiment on a simulated Instagram feed, results reveal that ad-context congruence enhances luxury perception for unfamiliar brands, while well-known brands maintain strong luxury associations even in incongruent contexts. Interestingly, processing fluency is negatively related to luxury perception, suggesting that greater cognitive ease may dilute perceptions of exclusivity.