Background: Self-care is a fundamental aspect of health, encompassing conscious and purposeful actions by individuals for themselves, their children, and their families to maintain health. Objectives: This study aimed to determine the effect of an educational intervention based on the Health Belief Model (HBM) on self-care behaviors among health workers in comprehensive urban health service centers in Rudbar in 2019. Methods: In this quasi-experimental study, 89 health workers from comprehensive urban health service centers in Rudbar city, Gilan, participated. The participants were randomly assigned into control and intervention groups. An educational intervention, consisting of five 60 - 75 minute sessions based on the HBM, was designed and implemented for the intervention group. Outcome data were collected before and three months after the educational intervention using a questionnaire that measured HBM constructs and health-promoting self-care behaviors. Data analysis was performed using the chi-square test and Mann-Whitney U test. Results: The age range of most participants (43%) was 30 - 39 years, and 86% of participants were female. Both experimental and control groups were comparable in demographic characteristics, HBM constructs, and health-promoting self-care behavior at pretest. The educational intervention based on the HBM improved the mean scores of the HBM constructs (except for perceived benefits) and dimensions of self-care behavior (P < 0.05 for all). The average score of self-care behavior in the intervention group increased from 128.4 before the intervention to 148.37 after the intervention. Conclusions: According to the results, using the HBM, with its suitable methods and structure for engaging employees actively, was effective for designing educational interventions to promote self-care behaviors in health workers. Therefore, it can be used as a suitable framework for planning educational interventions to enhance self-care behaviors among health workers.