‘AU Buck III’ is a new and distinct Chinese chestnut cultivar that is blight resistant, precocious and an annual bearer. It produces a medium to heavy crop load each year and a medium sized nut. Nut drop begins about September 25 and continues for a 4–5 week period. A large percentage of the nuts drop during the first three weeks of the period that nuts drop from this cultivar. ‘AU Buck III’ is a small to medium sized tree that is round in shape with low, dense, and spreading branches that was 6.71 meters tall, with a canopy covering an area of 41.85 square meters at 20 years old. ‘AU Buck III’ is the third cultivar to mature and drop nuts in a series of four Chinese chestnut cultivars that will provide for a continuous nut drop of a high energy wildlife food source from late August through mid-to-late November.