Kenpachi is a tall, muscular Shinigami with a wild and aggressive appearance, which fits his personality. He has a long face with pronounced cheekbones, and pronounced, hairless eyebrow ridges. He has green eyes and long, stringy black hair that grows out past his shoulders. A notable trait in his appearance is a long, thin scar running down the left side of his face, which was inflicted on him by Retsu Unohana when he was a child. He is one of the tallest Shinigami, towering at 202 centimeters (approximately 6 feet 8 inches), making him almost twice the height of his lieutenant, though shorter than Captain Komamura.
He wears a sleeveless captain's haori (which belonged to the previous captain of the 11th Division and took it after his defeat), which had a ragged look to it, as well as a lavender coloration on the coat's underside, and also the 11th Division's rhombus number on the coat's back, with the Gotei 13's symbol. Kenpachi also wears a special eyepatch on his right eye (which he uses to conceal his immense spiritual power). The design of the eyepatch is single one and the color is black with a grey outline.
Although he is known to be a violent fighter, Kenpachi's actions tend to be for the best. He has a very poor sense of direction, at times asking Yachiru for help (even though her sense of direction is just as bad). Kenpachi lives for battle, and enjoys a good fight more than anything. He even holds back in an effort to make any fight last longer. He claims injury and death are nothing but the price one pays for a good fight. Despite his division being the most blood-thirsty squad of the Gotei 13, the 11th Division has its own code of ethics, which is different from the rules and regulation of Soul Society. Despite his tendency to be brutal, Kenpachi usually stops a fight if his opponent is too injured to fight back, claiming he is not interested in fighting "weaklings who can't fight anymore", and he does not feel obligated to deal a death blow to anyone who cannot fight any longer. However, he will unhesitatingly kill his opponent if they refuse to end their fight, as seen during his battles with Kaname Tōsen and Nnoitra Gilga.
On multiple occasions, Kenpachi has shown to greatly respect those who can defeat him in a fight and those who can push him to his limit. Ever since Ichigo handed him his first known loss since becoming a Captain (though Ichigo considers their fight a loss for him), Kenpachi has considered the latter a member of his Squad. He expresses his willingness to engage him in a rematch every time they meet, only to be turned down, as Ichigo already considers themselves as friends. Nevertheless, Kenpachi still challenges him to a duel, as evidenced when he aided Ichigo in his fight against the Bount (where he gave "his blessing," stating doing so would make Ichigo stronger for "their anticipated fight").
Kenpachi sometimes contradicts his own logic in fighting. On the one hand, Kenpachi wishes to increase his own personal power. On the other hand, he conceals his strength to enjoy a fight for as long as possible. Although he thrives for battle, Kenpachi does have emotions. Kenpachi and his lieutenant, Yachiru, have been close ever since they met, and have a father-daughter-like relationship, making Yachiru one of the few people he cares for, along with 11th Division 3rd Seat Ikkaku Madarame and 11th Division 5th Seat Yumichika Ayasegawa. However, he has stated if his subordinates interfere in his fights, he will "cut them up first". Aside from Yachiru, Kenpachi deeply gives meaning to his name. Following his fight with Ichigo Kurosaki, Kenpachi talks about the pain of not having a name, as he lived his early years without one. This causes him to feel guilty his sword is not acknowledged by its own name. Since then, he has strived to learn its identity.
Kenpachi strongly believes fun comes before working. In every battle, he tries to get as much enjoyment out of it as possible. One example is when Kenpachi sends his 5th seated officer, Yumichika, to fend off the Bount in Karakura Town, as he is the only high-ranking officer who is not busy, or rather, busy having fun, as Yachiru was snacking and Ikkaku was napping. During his free time, Kenpachi always takes his afternoon nap. He does not have a particularly favorite dish, but he particularly hates nattō.
It seems that Kenpachi sometimes contradicts his own logic in fighting. On the one hand, Kenpachi wishes to increase his own personal power. On the other hand, he conceals his strength to enjoy a fight for as long as possible. Irrational to a certain extent, Kenpachi is one of the most complex characters in the Bleach series, as he exhibits a wide range of traits: lethargic, bloodthirsty, rebellious, aggressive, empathetic, honorable and wise.
Master Swordsman Specialist: Due to the lawlessness of the Zaraki district, Kenpachi's skill with his sword has been honed to a masterful level, letting him strike multiple times with changes of attack type (from slash to pierce) without any difficulty. His unpolished skills, but immense might with his sword allow him to always fight with one hand free, only using both hands when facing opponents he feels will beat him otherwise, as shown with Nnoitra and momentarily Ichigo. As the captain of the 11th Division, which specializes in sword fighting, he is among the most, if not the most, proficient swordsmen in all of Soul Society.
- Kendō: Kenpachi possesses considerable knowledge and skill in Kendō, which Yamamoto forced him to learn before officially joining the Gotei 13, though the training only lasted a day out of fear that Zaraki would become too powerful. However, Kenpachi, who despises using skills and techniques learned from another source, only uses Kendō as a last resort.
- Ryōdan (Bisection): A technique which Kenpachi uses when he is gripping his sword with two hands. It allows one to split an opponent down the middle.
Tremendous Spiritual Power: Even by a captain's standards, his Reiryoku is absolutely monstrous. Kenpachi has fought on par with two other captain-level opponents while still wearing his energy-sealing eye patch and his opponents releasing their Zanpakutō's Bankai. Ganju Shiba estimated his sealed power to be close or at the same level as Byakuya Kuchiki's Reiatsu. Retsu Unohana, one of the most powerful captains of the Thirteen Court Guard Squads, stated she was weaker than him even while he was still a child. Similar to Ichigo, when unleashing a strong enough surge of energy, it becomes visible and golden-yellow in color, sometimes with the appearance of a skull.
- Unruly Reiatsu Control: His spiritual energy can affect entire areas to the point of disrupting energy attacks from enemies, and cause others from seemingly miles away to enter a state of paralysis and confusion. Kenpachi can exert enough Reiatsu to repel the poison of Konjiki Ashisogi Jizo. Over time in a year and a half however, he has learned to control his spiritual power for a bit and has learned to use his power to stand in midair like other Shinigami.
- Damage Resistance: He can also use it as a sort of armor, making it impossible for him to be harmed by nothing less than the most skilled or powerful opponents. This is first demonstrated when Ichigo tries to cut Kenpachi at the start of their fight. Kenpachi allows Ichigo to strike him, yet not only does he fail to cut him, but Ichigo's hands start to bleed because of it. This is comparable to an Arrancar's Hierro.
- Shock Wave: He has also demonstrated enough control to focus and unleash his spiritual pressure in the form of a powerful shockwave. When using both hands, his shockwave can cause a huge radius of destruction.
- Energy Wave: By striking at the ground, Kenpachi can create an overflowing wave of yellow spiritual energy, which surges forward before crashing into Kenpachi's target.
Hakuda Expert: While preferring to use his blade in battle, Kenpachi has proven several times to be very dangerous while barehanded. He can easily catch an opponent's attack with a single hand, perform powerful punches and kicks, and easily subdue opponents with throws and take-downs. He even has demonstrated superb skill with throwing weapons. Kenpachi easily overwhelmed several members of the Onmitsukidō, a corp of Hakuda-specialists, despite being battle-worn.
Highly Perceptive Combatant: Despite his seeming disregard for any strategy in his fights and his self-admitted aversion to thinking during battle, Kenpachi is a very insightful man, regularly showing more understanding than one would expect. Even Byakuya was impressed by Kenpachi's ability to understand things he has no personal experience with. He is very adept at finding and exploiting weaknesses in his opponents' techniques, such as in his battle with Kaname Tōsen, where he subdued the latter's Bankai while armed only with a Zanpakutō and the one sense left accessible by Tōsen's Bankai at the time - touch. He is adept at adjusting to his opponent's attack patterns and battle methods to better counter them. While he admits to having no sanity or common sense, Kenpachi is very perceptive, noticing traits in people others would not notice, and seeing what drives a person's actions. He correctly singles out Kaname Tōsen and Gin Ichimaru as the only captains who are afraid to die. He possesses sharp intuition towards incoming danger, as shown by his ability to repeatedly dodge Tōsen's assault while still affected by his Bankai.
Immense Strength: Kenpachi possesses a very large degree of physical strength, most commonly displayed by his ability to fight back his opponent's attacks with a single arm. He has repeatedly displayed his strength with acts like kicking Tōsen through a building and slamming Komamura over his shoulder with one hand during their battle, as well as when he grabbed Ichigo's giant sword barehanded and reeled both him and the sword in for an attack. While fighting Ichigo Kurosaki, he rammed his sword through a building. With just his bare hand, Kenpachi deflected the Cero of the Quinto Espada, Nnoitra Gilga. His sword attacks can cut through Yammy Llargo's released state Hierro, removing his limbs in a single strike and knocking the giant Arrancar off his feet. He can fend off an opponent's gigantic sword with a single hand. His extreme cutting strength is evident in his ability to easily cut through an Espada's Hierro, which is harder than steel, as well as slice apart a skyscraper with a mere flick of his wrist
Immense Speed: While he possesses no known skill in Shunpo, Kenpachi is deceptively fast for his size and build. Thanks to his tremendous raw power, Kenpachi's leg strength allows him to more than make up for his lack of Shunpo, allowing him to move fast enough to instantly close a huge gap of space between him and his opponent, and even seemingly disappear from sight. In battle, he can strike with incredible speed in rapid succession, making it highly difficult for his opponents to find an opening and counterattack. During his short battle with Byakuya, Kenpachi manages to keep up with his opponent's incredibly fast Shunpo, a feat which shocked and impressed Byakuya.
Immense Endurance: His physical strength and speed is matched by his resilience. Kenpachi often ignores most of the injuries he sustains in battle (much like a berserker), not suffering any debilitation despite having multiple slash wounds in his body. He allowed himself to be stabbed during his fight with Tōsen just to grab Tōsen's blade to dispel his Bankai's effect. During his battle with Nnoitra, he suffered numerous slash wounds and was even impaled and almost beheaded with no visual impairment of his fighting abilities, Nnoitra noting most people would have already been dead by then. Even after receiving grievous injuries which left him in a comatose state, he recovered only days later, well enough to resume training.
Immense Durability: As resilient as Kenpachi is, he is just as hard to damage. During his battle against Yammy, while Kenpachi was focusing his attention on Ichigo, Yammy delivered a powerful blow with his massive fist, launching Kenpachi several meters and smashing him into a large pillar. Despite the impact, Kenpachi quickly emerged unfazed, claiming it was only a "decent punch" and Yammy needed to "put some effort in it".
- Shikai: Despite not knowing its name, his Zanpakutō is in a constant release state much like Ichigo's Zangetsu. The blade is much longer than that of a standard Zanpakutō, roughly the size of a nodachi (Field Sword) with a guard that extends inward from its center similar to a shinai. The hilt is white although most of it is wrapped in bandages, as is his sword's sheath. Despite constantly being in its Shikai state, Kenpachi’s Zanpakutō does not grant him any additional abilities due to their lack of communication. A further consequence of their disharmony is that it leaves the Zanpakutō with little spiritual energy and becomes easier to damage, ironically making its appearance a reflection of Kenpachi's own practice of weakening himself to fight others on an even level: it is a chipped and seemingly worn-down blade. Despite its appearance, it is easily capable of cutting through most objects. This is demonstrated when he stabs straight through the Shikai form of Ichigo's Zanpakutō and later slices a building in half with careless effort after releasing the full force of his spiritual power.
Eyepatch Power Seal: Kenpachi wears an eyepatch, created by the Shinigami Research and Development Institute just for him, which seals the bulk of his Reiryoku. Since he has so much power, however, it does not noticeably hinder him in battle; in fact, he remains just ahead of most other captains. His reason for wearing it is since he loves fighting so much, he cannot fight most opponents at full strength without defeating them quickly.
- Yachiru Kusajishi (Adoptive Daughter and Lieutenant)
- Ikkaku Madarame (Third Seated Officer)
- Yumichika Ayasegawa (Fifth Seated Officer)
- Team Karakura
- Toshiro Hitsugaya
- Byakuya Kuchiki (also rival)
- Retsu Unohanna (to a degree, also an old rival)
- Ganju Shiba
- Laxus Dreyar
- Thunder God Tribe
- Ryuha Armament Alliance
- Sosuke Aizen
- Kaname Tosen
- The Arrancars
- The Espada
- The Bounts
- Maki Ichinose (Former squad member)
- Kageroza Inaba
- The Reigai
- Oko Yushima
- Sojiro Kusaka