Background: Stunting is primarily a public health concern in Low- and Middle-Income Countries (LMIC). The involvement of Integrated Health Service Post (Indonesian: Posyandu) cadres is among the strategies to combat stunting in Indonesia. Objective: This study aimed to determine the effect of a short course on cadres’ knowledge. Method: A single group pre-test post-test design was conducted in Yogyakarta, Indonesia, from March to May 2022. Thirty cadres were selected based on the following criteria: willingness to participate, the number of stunted children in their Posyandu, able to read and write, and full attendance at the short course. The knowledge scores were measured by a questionnaire using true and false answers after a short course (post-test 1) and 4 weeks later (post-test 2). We apply STATA 16 to calculate the Mean Difference (MD) using a t-test and a Generalized Estimated Equation (GEE). Furthermore, the adequacy of the short course was evaluated with in-depth interviews. Result: GEE analysis showed that after controlling for age, education, occupation, and years of experience, the short course improved cadres’ knowledge significantly on post-tests 1 and 2, i.e., knowledge regarding Children Growth Monitoring (CGM) (Beta = 6.07, 95%CI: 5.10–7.03 and Beta = 8.57, 95%CI: 7.60–9.53, respectively), Children Development Monitoring (CDM) (Beta = 6.70, 95%CI: 5.75–7.65 and Beta = 9.27, 95%CI: 8.31–10.22, respectively), and Infant Young Children Feeding (IYCF) (Beta = 5.83, 95%CI: 4.44–7.23 and Beta = 11.7, 95%CI: 10.31–13.09, respectively). Furthermore, the short course increased their self-efficacy, confidence, and ability to assist stunted children through home visits. Conclusion: The short courses consistently and significantly boosted cadres’ knowledge of CGM, CDM, and IYCF, and appropriately facilitated cadres in visits to the homes of stunted children’s home.