Postoperative bleeding is the most frequent serious complications after vacuum‐assisted breast biopsy (VABB). The aim of this study was to evaluate the clinical effect of using urinary balloon catheter to prevent postoperative bleeding after ultrasound‐guided VABB. From May 2016 to June 2018, 324 patients who underwent ultrasound‐guided VABB were randomized into the study group and control group. In the study group, an urinary balloon catheter was inserted into the excision cavity to prevent bleeding and hematoma. In the control group, compression with thorax pressure bandage was used for hemostasis. Postoperative subcutaneous ecchymosis and hematoma were recorded and compared between the two groups. The rates of postoperative ecchymosis and hematoma in the study group were significantly lower than that in the control group (5.6% vs 13.0%, P < .05; 8.0% vs 20.4%, P < .05). Among patients with lesions ≤1.5 cm, the rates of postoperative ecchymosis and hematoma were 2.9% and 4.3% in the study group, 6.5% and 11.7% in the control group, but there was no statistically significant difference between the two groups (P > .05). Among patients with lesions >1.5 cm, the rates of postoperative ecchymosis and hematoma in the study group were significantly lower than that in the control group (7.6% vs 18.8%, P < .05; 10.9% vs 28.2%, P < .05). Hemostasis with balloon urinary catheter is a safe and effective method to prevent postoperative bleeding after VABB.