Parental migration is detrimental to children’s health and affects their behaviors which significantly happens in the poverty-stricken community in Bangladesh, especially in the northern region (Monga area). But little is known about the health status of this region’s left-behind children (LBC). This study identified the health-related factors associated with parental migration among left-behind secondary school children in the Monga areas of Bangladesh. A cross-sectional study was conducted in Lalmonirhat and Kurigram districts under Rangpur Division from January to March 2021. Data were collected from 400 secondary school-going children of classes VI-X aged 11 to 18 years by face-to-face interview method using a standardized and structured questionnaire. The Snowball sampling technique was employed to select the respondents. Univariate and bivariate statistical analyses were performed to analyze the data and to attain the objective. The results revealed that more than twothirds of the total respondents were aged 13-15 years (mean age =14.4 years) and there were 54.50% female children. Among the respondents around 28.5% were found in class VII, and 51.75% of the students were LBC. Around two-fifth respondents’ fathers were migrated and they were migrated due to poverty for a long time (≥84 months, mean time = 106.57 months) and they met to their children very often (n = 113, 54.59%) by six months (mean time = 6.31 months). During parental migration, most LBC were engaged in household works, and their academic performance was found unsatisfactory. Almost all LBC replied that their parental migration has impacted bad effects on their health (80.19%), they were suffering from different types of health complications (20.29%), and importantly they were mentally depressed (65.22%) though their body mass indexes (BMI) Z-scores were found normal. Different types of demographic factors (age, number of siblings, parental education and profession, housing condition, working status beside study, having family loan, present academic result), and health-related factors (having health complications, availability and place of healthcare services, suffering from depression, taking meals three times in a day, taking tiffin in schools, BMI Z-score, and having sanitary latrine) are significantly associated with LBC status. To better engage the LBC and promote their mental health, community-based interventions may help them. Social leaders as well as school teachers may contribute to LBC’s mental development through counseling. Government should take effective policies and programs for the development of LBCs’ well-being and education.