Ovarian hyperstimulation syndrome is a disorder associated with ovulation induction and is rarely seen in pregnant women. Very few cases of spontaneous ovarian hyperstimulation syndrome have been reported in a woman who is neither pregnant nor undergoing ovulation therapy. This case report describes how spontaneous ovarian hyperstimulation syndrome is associated with primary hypothyroidism in a 25-year-old, nonpregnant woman who is not on ovulation induction therapy. Imaging and laboratory findings confirmed the diagnosis of this rare entity, which aided the clinicians in providing prompt management and in preventing further complications.