Bangladesh is a country of natural disasters and climatic hazards, which frequently affect its inhabitants' lives and livelihoods. Among the various risks and disasters, floods are the most frequent hazard that makes haor households vulnerable. Therefore, this study was undertaken to estimate livelihood vulnerability to flooding within the flood-prone haor ecosystem in Bangladesh. Primary data were collected from 100 haor households each from Kishoreganj, Netrokona, and Sunamganj districts (N = 300) by applying a multistage random sampling technique. Data were collected through face-to-face interviews using a pretested structured questionnaire. The Livelihood Vulnerability Index (LVI) and the Intergovernmental Panel on Climate Change (IPCC) framework of vulnerability were applied to compare vulnerabilities among the selected haor-based communities. The empirical results revealed that haor households in Sunamganj district were more vulnerable to flood hazard and natural disaster in terms of food, water, and health than households in the other two districts. Taking into account the major components of the LVI, the IPCC framework of vulnerability indicated that households in Sunamganj district were the most vulnerable due to their lowest adaptive capacity and highest sensitivity and exposure. These findings enable policymakers to formulate and implement effective strategies and programs to minimize vulnerability and enhance resilience by improving the livelihoods of the vulnerable haor households of Bangladesh, especially those in Sunamganj district.