Back pain and its associated complications are of increasing importance among military members. The sacroiliac joint (SIJ) is a common source of chronic low back pain (LBP) and functional disability. Many patients suffering from chronic LBP utilize opioids to help control their symptoms. Platelet-rich plasma (PRP) has been used extensively to treat pain emanating from many different musculoskeletal origins; however, its use in the SIJ has been studied only on a limited basis. The patient in this case report presented with chronic LBP localized to the SIJ and subsequent functional disability managed with high-dose opioids. After failure of traditional treatments, she was given an ultrasound-guided PRP injection of the SIJ which drastically decreased her pain and disability and eventually allowed for complete opioid cessation. Her symptom relief continued 1 year after the injection. This case demonstrates the potential of ultrasound-guided PRP injections as a long-term treatment for chronic LBP caused by SIJ dysfunction in military service members, which can also aid in the weaning of chronic opioid use.