A 30-year-old female patient was referred to our institution due to vitreous hemorrhage. Best corrected visual acuity of her right and left eyes at her initial visit was 10/20 and 20/20, respectively. Although hypochromic iris was observed in the superior iris between the 10 and 2 o'clock positions in her right eye, her entire left eye exhibited hypochromic iris. Hypopigmentation of the fundus was seen in the superior part of her right eye. This eye also had a huge neovascularization on the optic disc that was 7 discs in diameter. Conversely, her left fundi showed hypopigmentation of the fundus in the entire region of the left eye, and dot hemorrhages were observed all over the left fundi, although no neovascularization could be seen microscopically. Fluorescein angiography showed a huge neovascularization in the right eye and a tiny neovascularization in the left eye. Gene analysis revealed the presence of the PAX3 gene homeobox domain mutation, which led to her being diagnosed as Waardenburg syndrome type 1. Magnetic resonance angiography showed there was no obstructive region at either of the internal carotid arteries and ophthalmic arteries. The severity of the diabetic retinopathy appeared to be correlated with the degree of hypopigmentation in the posterior fundus. We speculate that hypopigmentation of the fundus in Waardenburg syndrome may be responsible for the reduction in retinal metabolism, which led to a reduction in oxygen consumption and prevented further aggravation of the diabetic retinopathy. Only laser treatments using short wavelengths was effective in this case. While the extinction coefficient for hemoglobin when using green light is higher than when using yellow light, the differences between these wavelengths tend to disappear when oxygenated hemoglobin is present. To the best of the authors' knowledge, this is the first case report of a patient with Waardenburg syndrome and diabetic retinopathy.