Nigrospora sphaerica (Sacc.) E.W. Mason is a seriously damaging pathogen causing leaf blight on a few plant species. In July 2018, a leaf blight of unknown etiology was observed on peanut (Arachis hypogaea Linn.) leaves in Wenchang, China. Initial symptoms included circular brown spots, 2 mm in diameter, surrounded by yellow haloes, gradually developing into circular or elliptical necroses of up to 6 mm in diameter. Symptomatic tissues were surface-sterilized with 70% ethanol for 30 s and 0.1% HgCl2 for 60 s, washed three times in sterile water and put on PDA at 25 °C. After 5 days at 25 ± 2 °C, the fungus developed flat, white and light-to-dark grey colonies, with white-to-dark brown septate branched hyphae. Conidia typical for Nigrospora were black, one-celled (10.2–14.6 μm), and borne singly at the tips of conidiophores. The internal transcribed spacer (ITS) region of the rDNA was sequenced using ITS1/ITS4 primers and accession No. MK482388 was 99% identical to N. sphaerica accession Nos. MG669225.1 and HQ608063.1. For pathogenicity testing, a conidial suspension (106 conidia ml−1) from a 7-day-old culture of N. sphaerica was used to inoculate ten leaves of yue-you 7 peanut cultivar, followed by incubation in a controlled environment chamber at 25 °C with 70–80% humidity. As a control, ten leaves of yue-you 7 peanut cultivar were inoculated with sterile distilled water. Two weeks after inoculation, symptoms were observed only on the leaves inoculated with conidia and the fungus was consistently re-isolated. Nigrospora sphaerica was observed on blueberry in Argentina, sugarcane in China, and tea in India (Cui et al. 2018; Dutta et al. 2015). To our knowledge, this is the first report of N. sphaerica on peanut.