β-Glucosidases are widely applied to biofuel production, food industry, and improvement in flavors. The novel β-glucosidase gene debgl was identified from the Arctic bacterium Devosia sp. Arc12 and expressed in Escherichia coli BL21 (DE3). The putative gene, belonging to the glycoside hydrolase family 1, consists of 1311 nucleotides and encodes 437 amino acid residues. The optimal temperature and pH of the recombinant DeBgl were 55 °C and 7, respectively. The recombinant DeBgl displayed salt and ethanol tolerance, and the Vmax, Km, and kcat for the substrate cellobiose were 754 μmol min−1 mg−1, 12.8 mM, and 661.4 s−1, respectively. The concentration of glucose was reached 51.6 g L−1 after incubation at 40 °C for 8 h in 100 g L−1 cellobiose solution. It suggests that the recombinant DeBgl is a good candidate enzyme to degrade complex celluloses. The signal peptide (SP) citH has been proven to be the most suitable for the secretory expression of β-glucosidase by screening the signal peptide library in Bacillus subtilis. The secretory activity of the SP citH fused DeBgl in the vector pMA5 was 9-fold higher than that of the DeBgl without signal peptide. This secretory expression system of β-glucosidase may benefit its industrial application.