Local radiotherapy or surgery is the standard of care for treating brain metastases among patients with breast cancer. However, affected by tumor subtype, more than 50% of human epidermal growth factor receptor 2 (HER2)-positive metastatic breast cancer and brain metastases will still develop local recurrence or new brain lesions within 1 year after radiotherapy. As systemic therapies demonstrate higher and clinically relevant levels of intracranial activity and longer survival, there is limited evidence to guide how to weigh the options of radiotherapy versus systemic therapy (and deferral of radiation) in patients with progressive brain metastases, particularly those that are symptomatic. This study presents a case of progressive symptomatic HER2-positive brain metastases in a patient previously treated with whole brain radiotherapy and various targeted therapies. Due to limited access to novel HER2-targeted drugs, a new antibody-drug conjugate drug, disitamab vedotin (RC48) monotherapy, was chosen for postprogression treatment. The patient experienced rapid relief of neurological symptoms, partial regression of the brain tumor, and sustained disease remission for over 12 months without any treatment-related toxicity, also avoided reirradiation exposure and potential neurocognitive decline. The treatment of brain metastasis has been a topic of ongoing discussion. Our experience may offer valuable insights into managing HER2-positive progressive symptomatic brain metastases.