Suicidal thoughts and behaviors (STBs) in both the United States (U.S.) and United Kingdom (U.K.) are on the rise. Identification of individual-level protective factors can better inform prevention and intervention efforts. However, the protective role of humor and grit are not yet fully understood. The current study (1) identified the potential protective associations of humor subscale (affiliative, self-enhancing, self-defeating, and aggressive) and grit on STBs among adults, and (2) explored the moderating role of country (U.S. or U.K.) on the relation between humor and grit with STBs. Participants (N = 832) completed self-report measures administered online: Humor Styles Questionnaire, Grit Scale, and Suicidal Behaviors Questionnaire-Revised. Moderation analyses were conducted using bootstrapping techniques. Aggressive humor was related to greater STBs, while grit was related to fewer STBs. Further, cross-cultural variation in humor styles and STBs were observed. Self-enhancing and self-defeating humor were significantly negatively related to STBs among participants from the U.K., but not the U.S. Therapeutically promoting self-enhancing and self-defeating humor as positive coping mechanisms may be beneficial for treating STBs among individuals in the U.K. Reducing aggressive humor may also have utility for suicide prevention.