Purpose: The present study was conducted to develop the Life Respect Enhancement Program and test its effectiveness on suicide knowledge, suicide intervention skills, self-efficacy in suicide prevention, and gatekeeper behaviors among nursing officers. Methods: The program was developed according to the ADDIE model and finalized after practical need analysis, expert verification, and a preliminary study. The present study used a concurrent embedded mixed-method research design. To compare the effects of the Program and the control group on the outcome variables, a quantitative study was conducted using a nonequivalent control group with a pretest-posttest design. Quantitative data were analyzed using c2-tests, t-tests, and RM-ANOVA. A qualitative study was conducted using FGI with six members of the experimental group 3 months after intervention completion. Results: In total, 56 nursing officers participated in the 3-month follow-up test. Compared to the control group, the experimental group showed significant improvements in suicide knowledge, suicide intervention skills, and self-efficacy in suicide prevention scores at post-test. The significant group differences in suicide knowledge and suicide intervention skills were maintained at 3 months. The gatekeeper behavior scores of the experimental group were also significantly higher than those of the control group at 3 months. Qualitative analysis of the participants’ experiences with the Program yielded two themes and seven sub-themes. Conclusion: The newly developed Life Respect Enhancement Program demonstrates significant effects on suicide knowledge, suicide intervention skills, and gatekeeper behaviors. Thus, this program is recommended to promote suicide prevention competencies among nursing officers in military clinical settings.