<p>Few studies have examined the effects of life history strategies on unethical decision making, and the underlying mechanisms are not well understood. On the basis of life history strategy theory and social cognitive theory, the present study established a chain-mediation model to investigate the relationship between life history strategies and unethical decision making by testing the mediating roles of moral identity and moral disengagement. 926 young adults completed an online questionnaire measuring life history strategies, moral identity, moral disengagement and unethical decision making. Results revealed the negative association between slow life history strategies and unethical decision making, as well as the chain-mediating role of moral identity and moral disengagement. Specifically, slow life history strategies can enhance moral identity, thereby reducing moral disengagement and ultimately reducing unethical decisions. These findings not only uncover the mechanism underlying the relationship between life history strategies and unethical decision making, but also provide practical implications for preventing individuals from making unethical decisions and engaging in immoral behaviors.</p>