This community service program was conducted to support the Ministry of Health’s specific interventions to accelerate stunting reduction, focusing on meeting the nutritional needs of mothers before and during pregnancy and of children aged 6–24 months. The program aimed to improve community knowledge and attitudes toward nutrition and stunting prevention through a knowledge–attitude–behavior (KAB)-based education model in Ngambarsari Village. Activities were integrated into Posyandu services, including anthropometric measurements, nutrition counseling, educational sessions for mothers of toddlers and adolescents, and the distribution of nutrition guidebooks to ensure sustainability. The study employed a Pre-Experimental Design with a One-Group Pretest–posttest approach without a control group. A total of 55 participants were included in the evaluation. Program effectiveness was measured by comparing pre- and post-intervention cognitive and affective scores using descriptive analysis, the Kolmogorov–Smirnov normality test, and paired t-tests. The results showed significant improvements in knowledge (p = 0.008) and attitudes (p = 0.003). The mean cognitive score increased from 87% to 91%, whereas the affective score increased from 86.0% to 90.3%. Community-based nutrition education effectively enhanced understanding of exclusive breastfeeding, complementary feeding, balanced nutrition, hygiene practices, and child growth monitoring. However, gaps remain in dietary supervision and routine growth monitoring practices, indicating the need for continuous assistance in this area. Overall, structured and collaborative community-based interventions can strengthen the local capacity for sustainable stunting prevention.