Introduction <p>Physical activity is a crucial aspect of health promotion, playing a significant role in preventing non-communicable diseases and reducing mortality. This study aims to assess the impact of an educational intervention, grounded in the theory of planned behavior, on the intention to engage in physical activity among middle-aged women attending comprehensive health service centers in Qom.</p> Materials and methods <p>This study is a controlled, semi-experimental interventional research. For sampling, a list of comprehensive health service centers in Qom city was first prepared as a cluster. Four centers were then selected using a simple random method: two centers were assigned to the intervention group, and two centers to the control group. Next, the list of middle-aged women who had visited and maintained health records at the selected centers was obtained. From this list, 70 women were randomly selected for each group (intervention and control). The educational content was delivered to the intervention group in four sessions of 35&#xa0;min each. The data collection tool was a two-part questionnaire. The first part included five demographic questions, while the second part focused on questions related to the intention to engage in physical activity, based on the theory of planned behavior. The questionnaires were distributed and completed by participants both before the educational intervention and 2&#xa0;months afterward. The collected data was entered into SPSS software (version 24) and analyzed using descriptive statistics, chi-square tests, independent <i>t</i> tests, and paired <i>t</i> tests, with a significance level of <i>p</i> value &lt; 0.05.</p> Results <p>The samples were homogeneous in terms of demographic variables, with no statistically significant differences (<i>p</i> value &gt; 0.05). The mean scores for attitude, subjective norm, perceived behavioral control, and behavioral intention to engage in physical activity showed no significant differences between the intervention and control groups prior to the educational intervention. However, after the implementation of the training program, the mean scores for all variables in the intervention group showed a significant increase (<i>p</i> value &lt; 0.001).</p> Conclusions <p>The findings demonstrate the effectiveness of the educational intervention, based on the theory of planned behavior, in increasing the intention to engage in physical activity among the middle-aged women studied.</p>