Chronic sialorrhea is a debilitating condition commonly seen in patients with neurological disorders such as cerebral palsy. RimabotulinumtoxinB (RIMA) is approved for treating sialorrhea, with a recommended dose range of 1500-3500 units. We report a case of a 48-year-old female with spastic quadriplegic cerebral palsy, profound intellectual disability, and chronic sialorrhea who was treated with progressively higher doses of RIMA, culminating in a dose of 20,000 units administered via injections into the parotid and submandibular glands. So far, the patient has received 22 treatment cycles of high-dosage RIMA spaced three months apart with remarkable improvement in sialorrhea without any severe adverse effects. This case demonstrates the potential safety and efficacy of using RIMA at a dose of 20,000 units for managing refractory chronic sialorrhea in patients with cerebral palsy, warranting further research into higher dosing regimens.