A jambiya (Arabic: جنبية), is a type of dagger with a short curved blade with a medial ridge that originated from the Hadhramaut region in Yemen. They have spread to other countries in the Middle East, to other countries in the Arab world, and to parts of South Asia and Southeast Asia. Men typically above the age of 14 wear it as an accessory to their clothing.

The jambiya was given its name because it is worn on the side of a person—the word jambiya is derived from the Arabic word janb (Arabic: جنب, lit. 'side'). A jambiya is constituted of a handle, a blade, and a sheath in which the blade is held. It is made of a certain sort of wood, to hold the blade that is fixed to the waist from underneath with an upward curved sheath. The belt that holds the jambiya is made of tanned leather, or some thick cloth. There are specialised markets and handicraft markets that decorate it with golden wires.

The jambiya were taken by travelers to other cultures including the Ottoman Empire, Persia and India, where they were adopted with slight differences to the blade, hilt and scabbard.

A significant part of a jambiya is its hilt (handle). The saifani hilt is made of rhinoceros horn, which can cost up to $1500 per kilogram; poaching of black rhinoceri for this purpose has led them to become critically endangered. It is used on the daggers of wealthier citizens. Different versions of saifani hilts can be distinguished by their colour. Other janbiya hilts are made of different types of horn, wood, metal and ivory from elephants and walruses. Apart from the material used for the hilt, the design and detail is a measure of its value and the status of its owner.

The double edged blade of the jambiya is constructed of steel that in some cases is Damascus or wootz steel. The blade is stored in a sheath known as 'Asib (Arabic: العسيب), usually made of wood covered with metal, leather or cloth. The sheath can be decorated with various ornaments that signify status. These include silver work, semi-precious stones, and leather. The sheath can be fixed to a leather belt, which is normally 2–3 inches (5.1–7.6 cm) wide. The belt is usually worn around the lower abdomen. There are often other items attached to this belt, such as a silver purse for containing money and change. Sometimes, Jambiyas are made from shrapnel left over from missiles in a war.

Despite the cultural significance of the jambiya, it is still a weapon. Although people have used it in times of dispute, there are societal norms that must be followed in order to avoid defamation. The jambiya should only come out of its sheath in extreme cases of conflict. It is also commonly used in traditional events, such as dances.

Like with some other curved knives, as the blade bends towards the opponent, the user need not angle the wrist, which makes it more comfortable as a stabbing weapon than straight-bladed knives. Its heavy blade enables the user to inflict deep wounds.

A jambiya is a short dagger worn by men in Yemen. The handle of a jambiya tells the status of the man who wears it.