Penile prolapse in guinea pigs may occur due to prolonged trauma, fur/debris accumulation, irritation and/or infection of the penis. Other species affected by penile prolapse include reptiles, horses, cats, dogs, degus and chinchillas. Treatment for penile prolapse usually involves treatment of the underlying cause, anti-inflammatories, analgesics and manual reduction. However, if initial manual reduction is unsuccessful and the penis continues to prolapse, surgical intervention may be considered to facilitate prolapse reduction. In horses, traumatic penile prolapse was successfully treated using a modified Bühner suture technique, historically used in reproductive prolapse in cattle. This case report describes the successful use of a modified Bühner suture technique to treat a four-year-old intact guinea pig boar with balanoposthitis-induced penile prolapse. Based on this experience, a modified Bühner suture technique in conjunction with appropriate medical management is a useful, minimally invasive technique for treatment of balanoposthitis-induced penile prolapse in guinea pigs.