Background and AimsDiseases transmittable by Aedes mosquito affect the health of millions of people every year, however, they can be effectively prevented. This study aimed to apply the Health Belief Model (HBM) in promoting preventive behaviors against dengue fever in southern Iran.MethodsIn this quasi‐experimental study, 320 people were randomly selected through multi‐stage cluster sampling in 2022 (161 in the intervention group and 159 in the control group). The data were collected using a researcher‐made questionnaire based on the HBM constructs before and 1 month after an educational intervention. Content validity index (CVI), content validity ratio (CVR), and Cronbach alpha coefficient were used for psychometric evaluation of the questionnaire. The educational intervention was made on a daily basis in a WhatsApp group in August and September 2022. Descriptive and inferential statistical tests were used for data analysis.ResultsAfter the educational intervention, the mean score increased in the constructs of behavior (38.42 ± 1.54), knowledge (10.77 ± 0.98), attitude (24.30 ± 1.59), perceived susceptibility (20.05 ± 1.42), perceived severity (21.31 ± 2.01), perceived benefits (28.00 ± 2.16), self‐efficacy (14.77 ± 0.51) of the intervention group. Moreover, after the intervention, the scores of perceived barriers (8.96 ± 1.31) decreased in the intervention group (p < 0.05). The analysis of covariance showed education had a statistically significant effect on HBM constructs.ConclusionsThe participants' knowledge about preventive behavior of dengue fever increased. They managed to remove the barriers to healthy behavior and began to show the desired preventive behavior with the self‐efficacy they gained; thus, the educational intervention based on the HBM can improve the behaviors to preventi of dengue fever, which is transmitted by the Aedes mosquito.