Knife throwing is an art, sport, combat skill, or variously an entertainment technique, involving an artist skilled in the art of throwing knives, the weapons thrown, and a target. In some stage performances, the knife thrower ties an assistant to the target (sometimes known as a "target girl") and throws to miss them.

Knife throwing in every application involves the same basic principles of mechanics. The objective in each case is for the point to stick into the target with a sufficient amount of force. For this to be successful, accuracy, distance, number of rotations and placement of the body all must be taken into account.

The thrower may throw with spin; that is, throw so that the knife rotates parallel to the direction of the throw during flight. This means that the thrower, assuming they are throwing the same way every time, must either choose a specific distance for each type of throw or, more practically, make slight adjustments to the placement of the knife in the hand or to the throwing movement. The way the knife is gripped can also be adjusted: If it is gripped by the blade when it is thrown, it will complete an odd number of half-turns, whereas if it is gripped by the handle, it will complete some number of full turns. So, if the thrower estimates they need one and a half turns for the point to hit the target, they would grip the knife by the blade before throwing. If they feel they need two full turns for it to hit the target point-first, they would grip it by the handle.

With the no-spin throwing techniques, the throwing motion is made as linear as possible, the knife's rotation being slowed even more by an index finger on the spine during release. Thrown no-spin, knives will make no revolution or only a quarter spin before reaching the target (point first), but no-spin throws are not as accurate or stable in flight as spin techniques.

The knife does not need to be sharp to stick; as long as it has a point, it will stick into the target.^{[citation needed]}

In the US and in many European countries, there are communities of people pursuing knife throwing as a sport, similar to archery. For example, in Europe more than 30 knife throwing clubs exist. The clubs are usually set up in a not-for-profit form and are run by sports enthusiasts.

The outdoor competition itself consists, in the most common form, of a series of straight throws aimed at a set of standard wooden targets or in some cases foam. Similar to an archery target, competition knife throwing targets have a bullseye surrounded by one or more rings. A sticking knife scores points. The thrower must be standing at least a set distance away from the target, with higher distances for more challenging events. The International Knife Throwers Hall of Fame (IKTHOF) keeps a ranking of its members based on their performance during these sponsored competitions. EuroThrowers maintains a register of the world records, and for each championship publishes the full scores together with the meetings' reports.

Urban Knife throwing is an indoor activity, with dedicated facilities providing lanes for rent. Like bowling, the focus is primarily recreational.