AbstractBased on previous research on blood donation incentives, we investigated the effectiveness of two incentives—eligibility for free blood transfusions and improving individual credit scores—and explored the psychological mechanisms underlying these effects. We conducted four studies to explore the relationship between incentives and blood donation intention. The results showed that eligibility for free blood transfusions was more effective than improving individual credit scores due to the mediating effect of perceived attractiveness. Meanwhile, improving individual credit scores failed to play an effective role and was significantly lower than eligibility for free blood transfusions due to the mediating effect of perceived threat to freedom. We further found that after adding the moderating variable of involvement, there was no difference between the two incentives due to the weakened mediating effects of perceived threat to freedom and perceived attractiveness in the high‐involvement group. This study establishes two effect paths from incentives to perceived threat to freedom/perceived attractiveness to blood donation intention, explaining the effectiveness of incentives.