Cyclic vomiting syndrome (CVS) is a disorder characterized by episodes of nausea and vomiting lasting 1 to 5 days, followed by asymptomatic periods. The etiology and pathophysiology of CVS are unknown, but CVS shares similar characteristics to those of migraine headaches. Tricyclic antidepressants have the most evidence and are generally effective for prophylaxis of further episodes in patients with CVS. Second-line pharmacotherapies typically target specific comorbid symptoms or conditions and may include antiepileptic or antimigraine drugs, benzodiazepines, antispasmodics, proton pump inhibitors, antiemetics, and analgesics. OnabotulinumtoxinA (ONABoNT-A) injections have not been studied in the population with CVS but are regarded as a pharmacotherapeutic option for migraine headaches. We describe a 45-year-old woman with a 5-year history of CVS who had failed previous typical prophylactic migraine and CVS pharmacotherapies and was referred to the neurology clinic for management of both of these conditions. On review, the neurologist noted a correlation of the patient's headaches with her CVS symptoms. ONABoNT-A injections were started at 155 units intramuscularly every 12 weeks for her migraine headaches, which also dramatically improved her CVS. The main adverse effect reported by the patient was numbness and weakness in her left shoulder after the injections, which are symptoms consistent with ONABoNT-A injection use; however, these symptoms typically resolved a few days later. Regarded as a pharmacotherapeutic option for migraine headache prophylaxis, ONABoNT-A injections have demonstrated modest efficacy in preventing migraine headaches. Clinicians should be aware that ONABoNT-A injections may also have a role in the prophylaxis of CVS.