Yuzu (Citrus junos, from Japanese ユズ or 柚子) is a citrus fruit and plant in the family Rutaceae.

The fruit looks somewhat like a small grapefruit with an uneven skin, and can be either yellow or green depending on the degree of ripeness. Yuzu fruits, which are very aromatic, typically range between 5.5 cm (2.16 in) and 7.5 cm (2.95 in) in diameter, but can be as large as a regular grapefruit (up to 10 cm (3.93 in) or larger).

Yuzu forms an upright shrub or small tree, which commonly has many large thorns. Leaves are notable for a large, leaf-like petiole, resembling those of the related kaffir lime and Ichang papeda, and are heavily scented.

Yuzu closely resembles sudachi (a Japanese citrus from Tokushima Prefecture, a yuzu–mandarin orange cross) in many regards, though unlike the sudachi, yuzu eventually ripen to an orange colour and there are subtle differences between the flavours of the fruit. The yuzu originated and grows wild in central China and Tibet. It was introduced to Japan and Korea during the Tang dynasty, and is still cultivated there. It grows slowly, generally requiring 10 years to fruit.  It is unusual among citrus plants in being relatively frost-hardy, due to its cold-hardy C. ichangensis ancestry, and can be grown in regions with winters as low as −9 °C (15 °F) where more sensitive citrus would not thrive.