Devil Fruits are, arguably, the biggest source of power in the world of One Piece. Eating these fruits grant tremendous power in exchange for the ability to swim. The One Piece world is full of some extremely strong Devil Fruits, the powers of which make their users very capable in various ways.
At the same time, there are some Devil Fruits that are aren't utilized to their very best and are, consequently, not talked about as much. These Devil Fruits are actually quite useful but, for various reasons, remain underutilized.
Updated April 23, 2022 by Rei Penber: Devil Fruits offer incredible powers to the eater and they hold tremendous potential within them. Under a competent user, every Devil Fruit can become extremely useful and while One Piece has seen quite a lot of skilled Devil Fruit users, there are some who have either failed or not been given the chance to show what their ability is truly capable of due to plot constraints. This list already includes the most underutilized Devil Fruits in the series, however, we decided to expand on it further and added even more powerful Devil Fruits to it.
12 Ope Ope no Mi
The Ope Ope no Mi is a Paramecia-type Devil Fruit eaten by none other than Trafalgar Law. While it is quite overpowered, it is still underutilized, surprising as that may be. Law's Devil Fruit is extremely powerful and can easily allow him to take down most people in a couple of blows. In combat, his heart swap ability can create chaos, yet Law never uses it against stronger opponents.
His Shambles technique can, technically, swap anyone whose Haki isn't too strong with anything that he likes. For instance, Law could easily have swapped Doflamingo with an underwater fish with his technique and defeated him without even trying. What's more, Law's Gamma Knife or techniques such as Shock Wille, bypasses all physical defenses and damages opponents from the inside. In theory, he should be able to crush the hearts of his opponents within an instant and end the fight.
11 Suna Suna no Mi
Crocodile's Suna Suna no Mi is yet another Devil Fruit that is quite powerful yet at the same time, underutilized. The fruit makes him a sand human who can create, control, and turn into sand. At the same time, he can even suck out the moisture from his surroundings and turn people into a husk on contact. This ability of his fruit hasn't been used as often as it could've been. Crocodile can also turn his entire surrounding into sand, akin to an awakened Paramecia user.
With this power, he creates massive sand storms, quicksand, and even worse, dehydrates his enemies slowly. For the sake of the plot, Crocodile needed to be heavily nerfed. However, after the timeskip, it is highly likely that he's much stronger than he was before and his ability could've become better as well. In the Alabasta arc, however, Crocodile's power was underutilized quite a bit.
10 Hobi Hobi no Mi
The Hobi Hobi no Mi is a Paramecia Devil Fruit eaten by Sugar of the Donquixote Pirates. The power of the fruit allows her to turn anyone she merely touches into a toy and then bind them down to a contract that they cannot break. Those who get turned into toys get their existence completely erased from everyone's memories, which is quite a scary ability, no matter which way one looks at it.
To nerf this Devil Fruit, Oda gave it to a young child, who ate it at the age of ten and stopped aging physically ever since. Under a better user, this fruit would be unstoppable and would completely wreak havoc against even the most skilled fighters in One Piece. Without a doubt, the Hobi Hobi no Mi is quite underutilized and if Oda wanted to, he could've made this fruit a much more threatening one.
9 Bara Bara no Mi
The Bara Bara fruit was eaten by Buggy the Clown, one of the former members of the Roger Pirates. This Devil Fruit gives buggy the power to split any part of his body and manipulate it freely within a certain range. Buggy is also impervious to any slashing attacks. Buggy's Devil Fruit could be used in some of the most incredible ways if only he was shown to be a bit more creative in the story.
8 Moku Moku no Mi
Vice Admiral Smoker's Moku Moku no Mi is a Logia-type Devil Fruit that allows him to produce smoke and transform it into it at will. This Devil Fruit is quite useful but is hardly ever shown to its maximum potential.
Smoker could easily reduce the visibility of his opponents with this power and even more importantly, lead to asphyxiation. If used properly, the Moku Moku no Mi is an incredibly powerful Devil Fruit and fans might see its true power later on in the story.
7 Numa Numa no Mi
Another Logia-type Devil Fruit, the Numa Numa no Mi was eaten by Caribou, a new rookie pirate. This Devil Fruit allows him to turn his body into a swamp, meaning he can make his body absorb anything and everything.
Caribou's swamp is known to be a bottomless pit. Theoretically, he should be able to use it to sink anything into his body, from giant ships to entire islands themselves. Sadly, the powers of this Devil Fruit remain underutilized due to the incompetency of the user.
6 Horo Horo no Mi
Horo Horo no Mi is Paramecia-type Devil Fruit that was eaten by Perona, a former member of the Thriller Bark Pirates. This Devil Fruit is incredibly powerful as it allows her to produce hollows that can bring even the strongest of people to their knees within an instant and demoralize them.
What's more, the scouting network offered by this fruit is incredible as Moria used its power to keep a lookout on the entirety of Thriller Bark and even the seas surrounding it. Horo Horo no Mi also has a lot of offensive power but due to Perona's rather small role, this Devil Fruit isn't allowed to be a threat.
5 Gasu Gasu no Mi
Eaten by the infamous scientist Caesar Clown, the Gasu Gasu no Mi is a Logia-type Devil Fruit that allows him to create and manipulate all types of gas at will. With his scientific knowledge, this Devil Fruit is extremely useful.
Caesar can even remove the oxygen from the air using this power, meaning even the strongest of people can't survive his ability if he uses it cleverly enough. Caesar's ability to manipulate poisonous gases is just as dangerous but sadly, his weakness means that he is nowhere near to being a threat to anyone.
4 Shibo Shibo no Mi
The Shibo Shibo no Mi is a powerful Devil Fruit eaten by one of the Sweet Three Generals of the Big Mom Pirates, Charlotte Smoothie. This Devil Fruit allows her to absorb moisture from anywhere, including the air. She can wring the moisture out of others and kill them with a mere touch.
What's more, she can store all the moisture within her body and gigantify herself, making her a massive threat to anyone. Smoothie is, unfortunately, not given the screentime she deserves, meaning her Devil Fruit remains severely underutilized.
3 Buki Buki no Mi
A Paramecia-type Devil Fruit, Buki Buki no Mi was eaten by Baby-5, a member of the Happo Navy and an ally of the Straw Hat Pirates. This Devil Fruit is incredibly powerful as it allows her to turn herself into any weapon at will.
So far, she has turned herself into several weapons, including a revolver, a missile, a sickle, and even a cannon. However, given that she can transform into any weapon, the power of nuclear weapons shouldn't be beyond her reach. If used properly this Devil Fruit could make her a threat with power similar to Ancient Weapon Pluton, which can wipe islands off in a single blow.
2 Bonney's Devil Fruit
Jewelry Bonney's Devil Fruit doesn't have a name yet and all its abilities have certainly not been revealed already, however, this fruit is one of the very best seen in the story. It allows her to alter anyone's age with each hand.
With one, she can drastically age anyone with a mere touch, and with the other, she can reduce anyone's age as much as she likes. Just a single touch is enough for her to win over any of her opponents but sadly, Bonney hasn't been involved in the story enough to show what she's truly capable of. Jewelry Bonney's Devil Fruit remains underutilized.
1 Hana Hana no Mi
Eaten by Nico Robin, this Devil Fruit is, undoubtedly, one of the most underutilized ones in the story, simply because it is too powerful. Robin's Devil Fruit allows her to sprout limbs or other body parts within a certain range from anywhere.
Speed and power are useless against her fruit, making her extremely difficult to take on in battle. If she wanted, Robin can easily sprout any part of her body from within the other person and defeat them but for the sake of the plot, Robin's Devil Fruit remains underutilized.