One-step fermentation is a cheap way to produce xylo-oligosaccharides (XOS), where production of xylanases and XOS is integrated into a single process. In spite of having cost advantage, one-step fermentation is still short in yield so far due to the limited exploration. To cope with this issue, production of XOS from wheat bran by recombinant Escherichia coli through one-step fermentation was investigated here. A xylanase gene belonging to glycoside hydrolase family 11 of Bacillus agaradhaerens was employed to construct recombinant E. coli. This xylanase showed maximal activity at 60°C and pH 8.0. Its activity retained more than 60% after incubation at 70°C for 4 hours, showing a good stability. The recombinant E. coli successfully secreted xylanases that directly hydrolyzed wheat bran to XOS in fermentation medium. The generated XOS consisted of xylose, xylobiose and xylotriose accounting for 23.1%, 37.3% and 39.6%, respectively. Wheat bran concentration was found to be the most crucial factor affecting XOS production. The yield reached 5.3 mg/mL at 10% of wheat bran, which is higher than previous reports employing one-step fermentation. Nitrogen source type could also affect XOS yield by changing extracellular xylanase activity, and glycine was found to be the best one for fermentation. Optimal fermentation conditions were finally studied by response surface optimization. The maximal yield emerged at 44.3°C, pH 7.98, which is affected by characteristics of the xylanase and growth conditions of E. coli. This work indicates that the integrated fermentation using recombinant E. coli is highly competitive in cost and yield for production of XOS.