Herein, we developed a new and practical catalytic system for the carbonylative synthesis of β-hydroxyesters. By using simple, cheap and air-stable cobalt(II) bromide as the catalyst, combined with pyrazole and catalytic amount of manganese, active cobalt complex can be generated in-situ and catalyze various epoxides to give the corresponding β-hydroxyesters in moderate to excellent yields. Mechanism studies indicate that pyrazole plays a crucial role in this reaction. Moreover, with the addition of catalytic amount of manganese, the active cobalt catalyst can be regenerated, which provide a possibility for reusing of the cobalt catalyst.