Abstract: Emotionality is a well-established strategy for boosting audience engagement on social media. While fact-checking is positioned to provide objective information, fact-checking posts on social media often involve heightened emotionality. How much emotionality is present and how emotionality influences audience engagement and public sentiment toward fact-checked targets remain largely understudied. Informed by social psychological frameworks explicating message-level factors influencing public engagement and sentiment, the present study examines emotionality in 49,270 fact-checking posts created by 10 United States fact-checking organizations on Facebook from 2017 to 2022. Results showed that emotionality in fact-checking posts significantly increased by 13.5% over the years. Editorial fact-checkers (e.g., Washington Post) used higher levels of emotionality than independent fact-checkers (e.g., snopes.com). Emotionality positively indicated public engagement as predicted. However, in both fact-checked true and false information, emotionality was negatively associated with the public’s sentiment toward fact-checked targets, suggesting a potential spillover effect on stories verified to be true. This study reveals that emotionality in fact-checking posts boosts social media engagement yet with the potential of compromising fact-checking effectiveness.