The high intake of fermentable carbohydrates may cause nutritional disorders and negatively affect animal performance. Thus, the research study aimed to determine the better roughage:concentrate ratio to improve the carcass traits and physicochemical quality of meat from feedlot-finished Santa Ines lambs. Diets were composed of Tifton 85 grass hay (Cynodon sp.) and concentrate (soybean meal, corn meal, urea, and mineral mixture) and consisted of five roughage:concentrate ratios of 88:12 (C12), 69:31 (C31), 50:50 (C50), 31:69 (C69), and 12:88 (C88). After 63 days the animals were slaughtered and carcass traits, the yield of commercial cuts, and physicochemical properties of meat were evaluated. The higher percentage of concentrate on roughage provided higher DM intake, better feed conversion, higher conformation, finishing, and carcass yield that resulted in heavier commercial cuts with higher fat content in the meat. The addition of 50% concentrate to the roughage improved the carcass traits, commercial cuts, and physicochemical parameters of the meat in a similar way to the diet with 88% concentrate, but with leaner meats, meeting the demands of the current consumer market.