The Thousand-Year Blood War arc
Byakuya and Renji attend the official funeral of Lieutenant Chōjirō Sasakibe. While waiting for the cremation to begin, Byakuya tells Renji of Chōjirō's abilities and loyalty to Yamamoto. He later attends a captain meeting where he is informed about Vandenreich's infiltration, and is ordered to prepare for war alongside other captains. When the Vandenreich attack Seireitei again, Byakuya is seated in front of a group of Shinigami as they notice the assault. He then later arrives to assist Renji in his fight against Äs Nödt and an unnamed Quincy, promptly disposing of the unnamed Quincy and preparing to activate his Bankai in an attempt to discover what seal the Vandenreich use to suppress them. However, upon activating Senbonzakura Kageyoshi, it is immediately stolen by Äs using an unknown device. Byakuya then stops Renji from using his Bankai, warning him that he must not lose it as well.
Byakuya is later notified via transmitter swords along with the other captains and lieutenants by Rin Tsubokura that Ichigo is currently heading to Soul Society.
Byakuya is attacked with his own power.
As Byakuya is attacked by Äs Nödt's arrows, he relays to a worried Renji that they would be foolish to attack together and that he should stand back and watch the fight so that he can have information on how to take down the enemy. Äs Nödt asks Byakuya if he realizes that he is experiencing fear, which is what is making it hard for him to mount an effective attack or defense against him. He further details that this fear is a result of a unique ability that is administered by his Heliel Phiel. Äs Nödt goes into a speech detailing the nature of fear and how commendable he is for being able to resist as long as he has against it. Byakuya attempts to strike the Quincy but he dodges the attack and counters grievously wounding Byakuya by impaling his hand through his chest. The Quincy also explains that this fear is real and not based on reason and therefore it is not something one can overcome. Byakuya moves to strike him but Äs Nödt moves out the way and activates his medallion, which brings forth a ring of multiple blades from "Senbonzakura Kageyoshi" floating about the Quincy, who uses the blades to attack Byakuya shredding the captain with his own power.
Byakuya Kuchiki dies.
Äs Nödt comments to Byakuya that there is nothing he can do as there is no way he can win against his own bankai using his shikai. Renji attempts to intervene using his own shikai. While Renji attacks Byakuya attempts to use his shikai against the Quincy who counters with a storm of "Senbonzakura Kageyoshi" the storm of blades are so powerful that they send Byakuya crashing into a nearby wall. Byakuya asks that Renji and Rukia forgive him as his Zanpakutō breaks into pieces and he apparently dies from his wounds.