Berberis gagnepainii, or Gagnepain's barberry, is a species of flowering plant in the family Berberidaceae, first described in 1908. It is endemic to China, known from Guizhou, Hubei, Sichuan, and Yunnan Provinces. Berberis gagnepainii is a shrub up to 2 m tall. The leaves are evergreen, simple, lanceolate to elliptical, toothed, the teeth tipped with short spines. The leaves and flowers are borne on short shoots in the axils of 3-parted spines. The inflorescence is a fascicle of 2-15 yellow flowers. The berries are glaucous (waxy), dark blue-black and oblong.