Beef cattle fattening is a potential income generating enterprise for the small scale farmers’ in haor areas. Thus, the experiment was conducted with the aim to observe the effect of urea molasses straw for fattening bull and contribution to the income generation for small scale farmers in haor areas. The experiment was conducted at the Noagaon village under South Sunamganj Upazila of Sunamganj district from January to April 2017. Ten farmers were selected for rearing and each farmer reared one bull (2-3 years old) for fattening. Two groups of animals, treatment group treated with Urea Molasses Straw (UMS) in diet and control group without UMS supplementation, were laid out with five replications in each group. Data on body weight gain and profitability data were collected and analyzed as Completely Randomized Design (CRD). Feeding of urea molasses straw with the dietary feed had shown a positive effect on weight gain. After the end of the experimental period, mean body weight gain (g day-1animal-1) for the treatment and control group were measured as 496.41 and 236.62 g, respectively. The body weight gains of these both feeding groups were insignificant during the first fifteenth days of the experimental period, however, the difference was significant (p<0.05) for the rest of the experimental period. Moreover, higher gross margin was found in the treatment group (Tk. 14,310) than the control group (Tk. 3,810). Therefore, a significant growth performance with a profitable income for the small scale farmers’ of haor areas might be promising from beef cattle fattening by dietary urea molasses straw treatment.