The Ponseti method has become a popular technique to treat idiopathic clubfoot. In most cases, a percutaneous Achilles tenotomy is required to correct residual equinus contracture. Bleeding has been reported as a complication of percutaneous tenotomy. We present a case of a baby who developed a pseudoaneurysm after undergoing an appropriate Ponseti percutaneous Achilles tenotomy at the age of 8 weeks. The diagnosis of pseudoaneurysm was confirmed by color ultrasonography, which showed active flow in the base of the mass. This complication has not been previously described after Ponseti percutaneous Achilles tenotomy. The large pseudoaneurysm mass together with an incomplete correction made bracing with straight last shoes and Denis Browne bar impossible, and the patient developed an immediate relapse of the clubfoot deformity. The relapsed deformity was successfully treated with 4 weeks of additional Ponseti casting, with an emphasis on applying pressure over the pseudoaneurysm by molding the cast. Repeat ultrasonogram at that time showed that the pseudoaneurysm completely resolved, making invasive treatment of the pseudoaneurysm unnecessary. Physicians should be aware that vascular injury could lead to pseudoaneurysm after performing this otherwise simple office procedure.