Mihawk is a tall lean man with black hair, a short beard, mustache and sideburns that point upwards. His nickname comes from his strangely colored yellow eyes, which resemble a hawk's eyes.
He wears black and red ornate clothing with a crucifix pendant that hides a little dagger, which gives him the appearance of a Spanish swordsman. His attire consists of a wide-brimmed black hat decorated with a large plume, and a long, open black coat with no shirt underneath, with red, flower-patterned sleeves and collar. He wears white (light purple in the anime) pants held up by a decorated belt and tucked inside overly large boots in comparison to his leg size.
He wears a kogatana around his neck, appearing as a golden cross-shaped necklace, and carries Yoru on his back. His large sword, which he keeps on his back at times when not in use, has a curved black blade, and is also in the shape of a crucifix, with a golden handguard decorated by red beads (which are blue and green in the anime), and a hilt wrapped in bandages, with a particularly big bead at his extremity.
At his home in Kuraigana Island's castle, he sports different pants and an open white shirt with a ruffled neck. When he met up with Zoro outside, he had a plain dark cloak draped over his shoulders. Twenty four years ago, during Gol D. Roger's execution, Mihawk did not have his beard, nor did he wear his hat, and his hair was scruffier and shorter. He already had his crucifix pendant, and sported what looked like a flower-patterned jacket. Although it cannot be directly seen, he did not seem to be in possession of Yoru at that time.
After the timeskip, he shows some more wrinkles near the eyes.
In Volume 63 SBS, Oda drew the Shichibukai as children. Mihawk is shown with many scratches and bruises from training. He used a bokken as his weapon. He dressed in a dark-colored open jacket, short pants, shoes and a light-colored belt.
Like many other characters he has a unique laugh, or uniquely to himself bearing two: "Wahhahhahha/Kukukuku."
Dracule Mihawk is possibly one of the most serious characters in One Piece; very little seems to surprise him, he rarely smiles, and he has only been seen laughing twice in the series so far. He takes the revelation about Luffy being Dragon's son in stride, despite the surprise of those around him. He never unnecessarily reveals emotions on the battlefield, even when he is trumped (such as "Diamond" Jozu intercepting his flying slash aimed at Whitebeard, or Luffy surviving his onslaught).
He displays a sense of honor which other Shichibukai seem to lack, with the exception of Bartholomew Kuma (before his final modification into PX-0) and the former Shichibukai Jinbe. He recognizes and respects the swordsman's code and he even permitted Roronoa Zoro the luxury of training at his hand for his dedication and selflessness. He is also unafraid to reference his title of "Greatest Swordsman in the World" in relation to himself, indicating a high level of confidence in his own abilities.
Mihawk is selective when it comes to fulfilling his duties as a Shichibukai, as evidenced by his history of poor attendance at Shichibukai summons, as well as his decision to hunt and harass some pirates over others. Zeff speculated that the reason Mihawk attacked Don Krieg and his men might have simply been because they disturbed his nap. Mihawk admitted that the only reason he followed them all the way back to East Blue from the Grand Line was to kill time.
Though he is the swordsman above all the world's swordsmen, Mihawk remains grounded. While he has obviously become jaded regarding the abilities of other swordsmen, he is able to recognize talent. In fact, he has a desire to see Roronoa Zoro surpass him after having witnessed Zoro's incredible will and determination after their battle. When he speaks to Zoro, he states he will wait for Zoro, no matter how long it takes and notes that he will continue to be the world's greatest swordsman, showing great confidence in his own skills and abilities. He also understands that Luffy's natural charisma and quick amassing of comrades is his most dangerous attribute.
Mihawk also shows some curiosity for the people he decides to attack. He attempted to strike Whitebeard just to see what the power distance between himself and Whitebeard was and he attacked Luffy just to see if fate is on Luffy's side or not.
He also appears to have a sense of hospitality, having tolerated (somewhat) Perona and Zoro's presence upon his return to Kuraigana Island right after the Whitebeard War; he even went as far as relay to Zoro the events that occurred concerning his captain, Monkey D. Luffy. In addition, he offered a boat to help the Straw Hat's swordsman, Roronoa Zoro, leave the island.