Chi blocking is a special ability that Ty Lee, and later the Equalists, utilize in combat against their enemies. When they block someone's chi, it renders their victim's muscles useless and disables their bending abilities. This earned Katara's fear and spite after Ty Lee blocked her chi in Omashu. Chi blocking is mainly used by nonbenders as a way of self defense or even an attack form.
Ty Lee was the first to demonstrate the use of chi blocking in combat. Among other feats, she was seen disabling Katara's waterbending with a series of jabs in her arms and back. When fighting Team Avatar, she rendered most of Sokka's limbs useless. Ty Lee made good use of it during a fight when she took down the entire Terra Team with some cover from Mai.
The concept of chi blocking was used by Team Avatar to destroy the Fire Nation drill by striking its pressure points, causing the drill to collapse upon itself. Ty Lee also defeated at least one of the Kyoshi Warriors, who were protecting Appa, with this ability. Disguised as a Kyoshi Warrior, Ty Lee once again paralyzed Katara, catching her by surprise. She also immobilized Sokka and Toph when Azula threatened the Earth King at flame point, forcing them to surrender.
The technique was used by Ty Lee when she was cornered by several boys at Chan's party on Ember Island. She attempted several times to use it on Suki during the Escape from the Boiling Rock, but Suki was on guard against it due to her past experience. Later, in the escape's aftermath, Ty Lee used it to paralyze Azula and temporarily block her bending when she was about to strike down Mai.
Ty Lee made friends with and joined the Kyoshi Warriors after giving them chi blocking lessons in prison. This probably means the Kyoshi Warriors are capable of utilizing the technique.
Seventy years later, members of the Equalists utilized chi blocking to combat benders during the Anti-bending Revolution. The Equalists, led by Amon, were an organization against the art of bending, and by extension, against benders themselves. To effectively combat benders, the Equalists utilized chi blocking as a means to counteract bending. Various new recruits of the Equalists were trained in underground chi blocking barracks in order to become skilled in the art, and thus being more effective against benders.
Chi blocking is utilized by hitting pressure points with "quick jabs" and "punches", and must be done rapidly, often giving little time for the recipient to react. Ty Lee hit those pressure points with relatively light jabs using her fingers and knuckles. Apparently, even people wearing strong, but not necessarily heavy, armor are not spared from its effects. It seems she could use any of her fingers, such as when she disabled Katara with her thumb. Ty Lee could also use her feet to disable others' chi flow with a swing of her foot. She used this method to fend off the boys who cornered her in Chan's house.
Although a very useful method of fighting, chi blocking is most effective against an opponent not expecting such a light blow to be so devastating. It is less effective against someone who either knows chi blocking or who has battled a chi blocker in the past. An example of this was seen when Katara successfully dodged Ty Lee's attempts to block her chi after having already faced Ty Lee in an earlier battle. Additionally, chi blocking cannot work against an opponent wearing specialized armor like that of the Metalbending Police Force.
Chi blocking stops the victim's chi flow, reduces their muscular strength, and disables one's bending abilities temporarily; this would be particularly devastating for people who rely solely on their bending. Ty Lee had shown the ability to be able to control the damage she did: when she first attacked Katara, she was still able to move, though not able to bend. When attacking the Terra Team, they could barely move, were powerless, and felt pain afterwards; Katara was unable to heal them, stating that their chi was completely blocked. Later, Ty Lee struck down Katara who was paralyzed from head to toe and fell to the ground motionless.
An accidental form of chi blocking was used twice against Combustion Man. On two occasions, his third eye was hit (once by a pellet resulting from Toph's attack and once by Sokka's boomerang, deliberately aimed at him), causing him to "misfire". On the second occasion, the explosion was strong enough to demolish a section of the Western Air Temple, which led to his demise.
- Chi blocking is likely inspired by the martial arts technique dian xue or dim mak, which purports to kill or maim by disrupting the body's flow of internal energy.
- Qigong (sometimes spelled Chi Gong), a form of traditional Oriental medicine, uses similar techniques and pressure points to help others' chi flow more easily and is considered a standard medical technique in Chinese hospitals.
- While at the San Diego Comic-Con 2011, Bryan Konietzko stated that chi blocking was not an art unique to Ty Lee, rather that it was ancient and "cloaked in secrets".
- Chi blocking also has some connections to Varma Kalai, an ancient martial art of Southern India. It is said to have later spread to China.