Exogenous carbohydrases are commonly added to monogastric animal feed to degrade non-starch polysaccharides (NSP) to improve zootechnical performance and nutrient digestion. In the current study, the effects of dietary supplementation of a new, intrinsically thermostable, monocomponent xylanase on intestinal parameters, zootechnical performance and carcass traits of broilers were evaluated. A total of 720 1-day-old broilers were randomly allotted to four wheat-based diets with different levels of xylanase (T1: control; T2: 30,000 U/g; T3: 45,000 U/g; T4: 90,000 U/g) and fed from 1 to 35 days of age. The data showed that xylanase supplementation reduced the intestinal viscosity significantly, especially in the ileum. Duodenum and cecum pH was not influenced by xylanase supplementation, while T3 treatment showed the lowest pH value in jejunum and ileum. Xylanase supplementation reduced significantly feed conversion ratio (FCR) without affecting feed intake (FI). T2 treatment exhibited a higher body weight gain (BWG) compared the other treatments. Live weight, carcass weight, legs, and liver weight were significantly higher in T3 and T4 treatments compared to T1. No significant differences on foot pad lesions were observed among the four treatments. In conclusion, dietary supplementation of this new xylanase significantly improves intestinal tract viscosity and affects beneficially broilers’ performance and carcass traits.