To determine the effectiveness of a web-based educational program regarding local healthcare planning by public health nurses (PHNs) in Japan. A single-blind randomized controlled trial. Full-time PHNs working for local governments across Japan. The primary outcome was nurses' self-perception of competencies in public health policy. The secondary outcome was self-perception of knowledge, skills, and perspectives regarding local healthcare planning. We analyzed intergroup differences using the intention-to-treat principle and the Mann-Whitney U-test. The intervention group received six web-based learning modules including substantial knowledge and skills regarding local healthcare planning based on the analysis, design, development, implementation, and evaluation model and adult learning theory. Totally, 273 PHNs registered, and 38 were excluded without completing the baseline survey; 235 were randomly allocated to either the intervention (n=118) or control (n=117) groups. Sixty-four participants in the intervention group completed the program. Over 70% of the participants lacked opportunities to learn about local healthcare planning. The intervention group showed significant improvement in self-perception of competencies, knowledge, and skills regarding local healthcare planning, except for items related to evaluation. The web-based learning program effectively improved participants' self-perception of competencies in local healthcare planning.