The study was conducted to determine the level of knowledge of farmers regarding fertilizer application in Boro rice cultivation and to identify the factors associated with it in the haor region of Bangladesh. Appropriate application of fertilizer leads to higher economic growth through 40-60% increase in crop output and inefficient fertilization causes lowers productivity. Hence, it is quite logical to understand farmers’ knowledge towards fertilizer application in rice and to determine the factors in applying fertilizer in rice of Bangladesh. The study findings might be assisted policymakers in designing more effective policies to increase the fertilizer application at an optimal level by farmers in rice. Moreover, the findings can be helpful for the academicians and extension experts to improve their studies and extension activities. Data were collected from 60 randomly selected farmers through a pre-tested structured interview schedule. Correlation tests were performed to explore the relationship between selected socio-economic characteristics of the farmers and their knowledge level concerning fertilizer application. The results revealed that education and agricultural training experience had a significant positive relationship with farmers’ knowledge, while age, annual household income, and cosmopoliteness were negatively but nonsignificantly related. Family size, farm size, extension media contact, and organizational participation showed no notable association with fertilizer knowledge. The findings suggest that improving education and providing effective agricultural training can enhance farmers’ understanding of proper fertilizer use. Strengthening agricultural extension services and implementing targeted capacity-building programs could therefore contribute to improved Boro rice productivity and sustainable agricultural development in Bangladesh.