To describe the first use of high-dose-rate yttrium-90 disc brachytherapy for choroidal melanoma. A 72-year-old patient had a cT1-category choroidal melanoma characterized by the presence of orange pigment, increasing subretinal fluid (SRF), and enlarging tumor thickness. It was treated with single-session, light-guided, light-defined yttrium-90-disc brachytherapy. A specialized handheld applicator provided with 4 encircling lights was used to guide plaque placement and localize treatment. Unlike low-dose-rate plaques, high-dose-rate yttrium-90 required only 3 minutes 39 seconds. In this case, treatment did not require episcleral sutures, muscle relocation, outpatient dwell time, or a second surgery. High-dose-rate treatment improved radiation safety by eliminating perioperative exposure to health care personnel, the community, and the family. At the 13-month follow-up, the SRF and tumor thickness were diminished. There was no secondary cataract, radiation retinopathy, maculopathy, or optic neuropathy, and the visual acuity was 20/20. Yttrium-90 brachytherapy allowed for single-surgery, minimally invasive, outpatient irradiation of a choroidal melanoma.© The Author(s) 2024.