Obstructive Sleep Apnea (OSA) is one of the most common sleep disorders. A mandibular advancement device (MAD) can be used to manage primary snoring and OSA cases. It is mostly indicated in cases with mild to moderate OSA. This case reports shows the successful management of severe OSA using MAD. A 34-year-old male presented to the orthodontic clinic with a diagnosis of severe OSA, apnea-hypopnea index (AHI) of 71 events per hour with symptoms of loud snoring, witnessed gasping, morning headache, and excessive daytime sleepiness. The case was managed using MAD to position the lower jaw in a forward position during sleep with 7 mm advancement. Progress sleep study results showed that the AHI reached normal levels, with only two hypopnea events per hour and a complete resolution of apnea episodes. The patient’s symptoms subsided after using MADs. This case report documents that severe OSA can be managed with MAD in suitable cases.