In Blox Fruits, Aura is an inner power that can significantly increase the users defenses and allow them to deal damage to Elemental Fruit users. It is also known as Haki. Aura can be obtained from the Ability Teacher located at Frozen Island. Pressing the "J" hotkey activates and deactivates the Aura ability on the PC. The higher the level of Aura, the lower the damage the player takes when getting hit by enemies. Upgrading Haki to the max stage allows the player to cover their entire body with a protective Aura.

To train Aura as a Natural or Beast Fruit user, the player needs to gather up a ton of NPCs and hit them all at the same time. Obtaining the full body Haki can be complex because the game does not tell the player how much Haki EXP they have earned. However, using the Logia AFK grinding method is one of the easiest ways to obtain the full body Haki.

There are enemies with Aura in Blox Fruits, such as Snow Lurkers, Military Soldier, and Marine. Activating the Haki can alter the sword colors from the standard black hue, but this only applies to some of the Second and Third Sea blades. If the player attacks an Elemental Fruit user without activating their Aura, they will receive a warning message.