Early marriage, defined as marriage under the age of 18, is widely recognized as a human rights violation with deleterious consequences on women's health and well-being. It persists as a significant global public health issue, predominantly being practiced in South Asian countries. In Countries like Bangladesh, this practice contributes to an increase in early pregnancies among women of reproductive age, further exacerbating adverse maternal and child health outcomes. While certain predictors of early marriage are recognized, additional investigation is warranted due to diverse socio-economic and demographic circumstances. This study, therefore, aimed to identify the prevalence and determinants of early marriage among women in Bangladesh. This study included a total weighted sample of 18,228 married women aged 18 to 49 years, extracted from the most recent nationally representative Bangladesh Demography and Health Survey (2017-18). We estimated the survey weighted pooled prevalence of early marriage among women and stratified by their different characteristics. We used multilevel mixed-effect binary logistic regression model and estimated the odds ratios (ORs) with their 95% confidence intervals (CIs) to identify the individual-, household-, and community-level factors associated with early marriage practice. All analyses were performed by Stata software version 18. Overall, 74.27% [95% CI: 73.15, 75.35] women got married before reaching the age of 18 years. Early marriage was more prevalent in Rajshahi (82.69%), Rangpur (81.35%), and Khulna division (79.32%). Women with higher education (OR = 0.10, 95% CI: 0.08, 0.12), husband's higher education (OR = 0.57, 95% CI: 0.48, 0.67), and non-Muslim women (OR = 0.46, 95% CI: 0.40, 0.52) were associated with a lower likelihood of experiencing early marriage. Compared to those household heads aged ≤35 years, the likelihood of early marriage among women was lower for those household heads aged 36-55 years (OR = 0.84, 95% CI: 0.76, 0.93) and >55 years (OR = 0.78, 95% CI: 0.69-0.88). Women aged 18-24 years (OR = 1.24, 95% CI: 1.10, 1.40), husbands with agricultural occupation (OR = 1.22, 95% CI:1.06, 1.41), middle wealth index level (OR = 1.14, 95% CI: 1.02, 1.28), family size five or more (OR = 1.21, 95% CI: 1.11, 1.31), and rural residence (OR = 1.17, 95% CI: 1.04, 1.30) were more likely to experience early marriage. This study underscores the alarming prevalence of early marriage among women in Bangladesh, with three-fourths experiencing early marriage, particularly in specific regions. Notably, women education and older household heads were significantly associated with a reduced likelihood of early marriage. Our findings suggest that culturally sensitive interventions should focus on empowering older household heads, alongside initiatives to increase awareness among younger household heads, and enhance education, particularly in rural and impoverished households. These efforts could potentially alter socio-cultural practices and reduce early marriage in Bangladesh.