Objective To investigate the effects of a positive psychology intervention program on anxiety, depression, and well-being in patients who had attempted suicide by poisoning, so as to prevent subsequent suicides post-discharge. Methods A total of 96 adult patients who had attempted suicide by poisoning were allocated into a control group and an observation group, with 48 in each, based on their admission sequence. The control group received standard care, whereas the observation group additionally received a positive psychology intervention program. Anxiety, depression, and overall well-being were compared between the two groups before the intervention, at discharge, and three months post-intervention. Results The observation group exhibited significantly reduced depression and anxiety scores, but significantly increased well-being scores compared to the control group. Statistically significant differences were observed in the time, group, and interaction effects between the two groups (all P<0.05). Conclusion The implementation of a positive psychology intervention program can alleviate anxiety and depression levels and improve well-being in adult patients who had attempted suicide by poisoning.