Begonia austroyunnanensis, a new species from Yunnan (China) is described and illustrated. This new species is similar to B. subhowii in having short erect stems, obliquely ovate leaves and white flowers, but can be distinguished by its stem, petioles and peduncle having conspicuous, red, linear dots and the much longer abaxial wing of the capsule. A detailed description, data on distribution, ecology and an illustration are provided.