In Bangladesh, rural–urban migration is widespread. Many earlier studies discussed the factors, patterns, causes, and consequences and the socio-economic and environmental impact of migration from the general perspective. However, rural–urban migration with a particular focus on particular communities or migrants’ employment profiles, for instance, farmers, is poorly described. In contrast, many farmers move from rural to urban areas every year in Bangladesh. However, the factors that affect farmers’ rural-to-urban migration are a primary concern to academia and key actors, as the country’s economy mainly depends on agriculture and farming. This paper, therefore, aimed to identify the underlying factors of the rural–urban (R–U) migration of farmers in Bangladesh. Data for this study came from phone interviews conducted with 254 migrant farmers living in city districts in Bangladesh. We adopted a three-step approach to select and identify factors that impacted farmers’ decision to move from rural to urban settings. First, we reviewed the extant literature and compiled more than 70 variables of interest relevant to farmers’ migration. Second, 30 variables were selected for data collection after consultations with key informants (KIIs) and informal discussions (IDs) with farmers and local community leaders. Besides, the Q-methodology was used to assess the level of importance of the selected variables. Lastly, principal component analysis (PCA) was performed to extract salient dimensions of farmers’ rural-to-urban migration, where 21 variables were detected that consistently exceeded a threshold value of 0.50 of communality for further analysis. Our findings show that six dimensions—i.e., individual, household, economic, attitudinal, spatial, and climate-induced extremes—significantly influence and contribute to rural urban migration decisions for farmers. Further, our results indicated that age, agricultural knowledge, household debt, seasonal famine/poverty (Monga), unemployment in rural areas, availability of anticipated job opportunities in urban areas, shortage of agricultural inputs, and river erosion significantly influenced farmers’ decision to leave their farms in Bangladesh. Findings from this study may be used as inputs in predictive models and benchmark guidelines for assessing trends and patterns of rural-to-urban migration and for the formulation of policy and programs targeting domestic migration in Bangladesh for proper urban planning and further rural development.