<p>The Haor region of Bangladesh is particularly vulnerable to flash floods, which occur with varying intensities almost every year. This study assesses the Knowledge, Attitudes, and Practices (KAP) related to flash floods in the Sunamganj district of Bangladesh. Data were collected through a semi-structured questionnaire survey, with 442 respondents participating in face-to-face interviews conducted in May 2022. Spearman’s rank correlation was used to determine the associations between KAP and Spearman’s rank correlation was used to determine the associations between KAP and the socioeconomic characteristics of the individuals. Over 90% of respondents reported that flash floods have become a disaster in Bangladesh; half of the participants had limited knowledge regarding the causes of flash floods; most (74.4%) respondents believe they should pay attention to the daily forecast; the majority (91.6%) require improved awareness for their families and communities, including relevant training activities; and 77.8% of individuals are raising the bases of their houses above flood levels. Participants reported good knowledge (74.4%), positive attitudes (60.4%), and good practices (64.5%). The outcomes of the logistic regression indicated that individuals with good knowledge, positive attitudes, and good practices had better socio-economic characteristics. The results indicate that older people with previous experience of flash floods are more inclined to implement appropriate preparation and reaction techniques, possibly owing to their accumulated experiential knowledge and increased risk awareness, which collectively strengthen their ability for adaptive behavior. Fishermen exhibited a significantly higher level of flash flood awareness than businessmen, likely due to their direct and frequent exposure to river environments and reliance on weather conditions for their livelihoods. The level of education among participants is recognized as a significant factor in assessing their preparedness for the flash flood hazard. Results showed that educated individuals utilize advanced risk mitigation practices (<i>p </i>&lt; 0.01) and possess enhanced knowledge (<i>p </i>&lt; 0.001) compared to illiterate individuals. This innovative study could aid local governments, non-governmental organizations, and policymakers in their efforts to mitigate flash flood risks.</p>