Background The experiment was conducted to evaluate the effect of tree lucerne dried leaves (TLDL) as a substituting supplement for noug seed cake, and wheat bran concentrate mixtures (CM) on feed intake, digestibility, growth, carcass characteristics and economic benefits using Washera sheep fed desho grass hay as a basal diet. Methods Twenty‐five male Washera sheep with an initial body weight of 16 ± 4.01 kg (mean ± SD) were used for both growth and digestibility trials which lasted for 90 and 10 days, respectively The experiment was conducted using a randomized complete block design having five blocks with five treatments (T1 = 0% TLDL + 100% CM; T2 = 25% TLDL + 75% CM; T3 = 50% TLDL + 50% CM; T4 = 75% TLDL + 25% CM and T5 = 100% TLDL + 0% CM). Results Significant (p < .05) differences were observed among treatments in total dry matter (DM), nutrients and metabolizable energy (ME) intake; as the level of TLDL increases total DM and nutrient intake decreased (p < .05) except neutral detergent fibre intake (NDFI) and acid detergent fibre intake (ADFI). Digestibility of DM, organic matter (OM) and crude protein (CP) were significantly reduced (p < .001) among the treatments increasing the substitution level of TLDL for local concentrate mixture, but non‐significant for fibre fractions digestibility. Similarly, body weight, average daily gain and feed conversion efficiency were significantly different (p < .01) and highest in T1 than other treatments, whereas lowest values of the same parameters were observed for T5. Non‐significant difference among treatments was observed in almost all of the carcass characteristics except for rib‐eye area that showed significant difference among treatment and was highest in T1 and T2 (low level of TLDL inclusion). The economic analysis showed that supplementation TLDL was economically feasible in which the net return of the treatments were 31.66 (T1), 30.68 (T2) and 30.34 (T3), 27.88 (T4) and 26.32 (T5) USD (United States Dollar). Conclusions It was concluded that TLDL could be used as alternative feed source by replacing concentrate mixture up to 75% (T4) which enhanced nutrient intake, digestibility and growth performance of Washera sheep. Finally, TLDL supplementation is recommended as replacement of CM up to 75% for its biological and economic feasibility.