Abstract This study examined how the linguistic politeness of fact-checking messages affects audiences’ belief accuracy and message acceptance by shaping their perceived face threat and psychological reactance. In 2 experiments with national convenience samples of South Korean adults, we manipulated linguistic politeness by using either honorific or non-honorific sentence endings—a well-established marker of linguistic politeness in Korean—in fact-checking news articles correcting misinformation about COVID-19 (Study 1) and refugees (Study 2). Study 1 (N = 240) found that fact-checking articles using honorific sentence endings were perceived as less face-threatening than those presenting identical content with non-honorific endings, which in turn increased belief accuracy and the perceived persuasiveness of the articles. Study 2 (N = 296) replicated the findings of Study 1 and extended them by demonstrating: (1) the effect of using honorific (vs. non-honorific) sentence endings on recipients’ perceived face threat was not moderated by their conspiratorial predisposition or need for cognition; (2) the effects of perceived face threat were mediated by psychological reactance; and (3) the sequential mediation also produced attitudinal effects. The findings are discussed in light of their theoretical and practical implications for designing effective fact-checking messages to combat misinformation in non-Western languages.