According to Law, the New World is divided into territories governed by the strongest pirates thanks to their brokers, similar to a huge crime syndicate. The most influential man in this world was Donquixote Doflamingo, by the pseudonym of "Joker". His defeat by the Straw Hat-Heart Pirate Alliance and detainment by the Marines dismantles his criminal enterprises leaving many of his purchasers deprived of the illegal merchandise they ordered.
Due to this nature, the underworld involves almost all of the world's main forces and strongest individuals:
- Yonko: As the most powerful pirates of the New World, they are involved in the Underworld.
- Supernovas: As formidable New World pirates, some of them has been involved in the Underworld.
- Capone Bege is the head of one of the Five Great Families of the West Blue and hence is heavily involved with the underworld. 
- Trafalgar Law: In order to dethrone Doflamingo and defeat Kaido, acted as Caesar Clown's affiliate. Furthermore, his actions led to the resignation of Doflamingo from the Shichibukai (later revealed as fake news).
- Kid and Killer: Despite not being brokers, they watched Caesar Clown's presentation of Shinokuni's power.
- Shichibukai: Some Shichibukai are or were involved in the underworld.
- World Government: Due to the World Nobles' involvement, the World Government cannot take action against the institution of slavery.
- World Nobles: They are the main group interested in the slave trade.
- Donquixote Doflamingo was a World Noble.
- Donquixote Rosinante: A commander in the Marines, he was a double agent in the Donquixote Pirates monitoring their black market activites and reporting them to the highest officers in the military.
- Marines: Some former Marines got involved in the Underworld after their dismissal or resignation and while on active duty.
- Vice Admiral Vergo: As Joker's mole, he acted to hide Caesar Clown's illegal actions.
- Former Scientist Caesar Clown: After the chemical weapon incident on Punk Hazard four years ago, he has been involved in the illegal trafficking of weapons.
- Former Admiral Aokiji: After resigning from the Marines, he could be involved in the underworld, as Donquixote Doflamingo and Smoker have speculated.
- Vinsmoke Family: A royal family of killers. The family patriarch, Vinsmoke Judge, is infamous throughout the Underworld.
- Fishman Island's bloody past is due to slavery.
- Two peaceful countries are interested in Shinokuni.
- A war against the Flower Country has been supported by Joker's weapons smuggling.
- The Franky Family previously participated in St. Poplar's black market as both sellers and customers.
- Former Roger Pirates Vice Captain Silvers Rayleigh tried to sell himself as a slave in the Sabaody Archipelago's Human Auctioning House to steal money to pay off his gambling debts.
- The brothers Kelly Funk and Bobby Funk are renowned hitmen in the underworld.
- Suleiman is a renowned killer of the underworld.
- The non-canon pirate Breed is affiliated with the underworld and has been able to get a SMILE.
- Several yet unnamed brokers (at least twelve) are shown watching Caesar's broadcast.
- Jack has affiliations with the brokers and has been notified about Caesar Clown's defeat.
- A man with a horns and a cowl on his back is also seen among the many silhouetted brokers and appears to be one of Jack's subordinates or at least a broker for the Beast Pirates since the Beast Pirates wear horns as one of their trademarks.
|"Joker" ‡||Pekoms||Tamago||Disco ‡||??????|
|Crocodile ‡||Saint Roswald||Saint Charloss||Saint Shalulia||Saint Jalmack|
|Saint Mjosgard||Kaido||Charlotte Linlin||Breed ≠|
|Kelly Funk||Bobby Funk||Suleiman ‡||Vinsmoke Judge||Vinsmoke Reiju|
|Vinsmoke Ichiji||Vinsmoke Niji||Vinsmoke Yonji||Germa 66|
|Franky ‡||Silvers Rayleigh ‡||Caesar Clown||Trafalgar D. Water Law ‡||Vergo †|
|Donquixote Rosinante ‡ †||Eustass Kid||Killer||Jack||Kuzan *|
- †: the character is deceased.
- *: the character's status is unknown. Hovering the symbol may give further details.
- ≠: the character is non-canon.
- ‡: the character is no longer part of this group. Hovering the symbol may give further details.
- Further information: Broker
One of the main scopes where the Underworld acts is the smuggling via brokers. This involves illegal goods, rare goods, slaves, and illegal weapons.
|Selling Type||Supplier / Producer||Seller||Purchaser||Good||Sold Price||Marketplace|
|Slaves||Kidnappers||Disco (only anime)||World Nobles||Boa Hancock; Boa Sandersonia; Boa Marigold||(auction)||Human Auctioning House (only anime)|
|Illegal Goods||-||-||Baroque Works||Dance Powder||-||-|
|Rare Goods||-||-||Franky Family||Adam Wood||200,000,000||St. Poplar|
|Slaves||Kidnappers||Disco (under Joker)||
World Nobles; Various Nobles
|Slaves||(auction)||Human Auctioning House|
|-||Disco||A Noble||Byron||600,000 (auction)||Human Auctioning House|
|-||Disco||A Noble||Pascia||7,200,000 (auction)||Human Auctioning House|
|Hound Pets||Disco||Charloss||Keimi||500,000,000 (auction)||Human Auctioning House|
|Illegal Weapons||Caesar Clown||Caesar Clown||Two peaceful countries||Shinokuni||-||Punk Hazard (via broadcast)|
|Devil Fruit||Marines||Diez Barrels||-||Ope Ope no Mi||5,000,000,000||Ghost Town of Minion Island|
In addition to the trading of items and slaves, certain services can also be purchased in the Underworld. It is the primary network in which to locate and hire assassins, such as the Funk Brothers and Suleiman. Additionally, the Vinsmoke Family has been known to hire out their kingdom's army, Germa 66, as a mercenary force, partaking in wars on behalf of anyone (including other kingdoms) able to pay them.
No information about the existence of the underworld before Donquixote Doflamingo's rise have been revealed so far. However, the tragic past of Fishman Island being a source country for slave trafficking is at least 24-years old.
In the last ten years, Donquixote Doflamingo built up his status as the most influential man in the underworld under the alias of Joker. Due to this, in the last four years, he offered the rogue Marine scientist, Caesar Clown, his protection from the World Government. Some time after gaining a powerful influence in the underworld, Doflamingo formed a three-way alliance with Caesar Clown and Kaido in order to create the SAD and Zoan artificial Devil Fruit, to create an army of Zoan users within the New World.
The Franky Family often sold the valuables procured from ship dismantling on the black market.
Crocodile's Dance Powder was the cause of Alubarna's civil war. When the World Government discovered it, they stripped Crocodile of his Shichibukai status  and jailed him first in a Marine prison and later in Impel Down's Level 6.
Water 7 SagaEdit
Water 7 ArcEdit
Summit War SagaEdit
Sabaody Archipelago ArcEdit
During the Straw Hat Pirates' visit to Sabaody Park, the Hound Pets captured Keimi and sold her to Disco. This caused Luffy to become enraged and attacked the Human Auction House, bringing about an incident with the World Nobles. Due to this, Doflamingo forsook Disco and gave him the entire establishment.
During the TimeskipEdit
Punk Hazard ArcEdit
During Caesar Clown's broadcast for the selling of Shinokuni, the Straw Hat Pirates, Trafalgar Law, and Smoker's G-5 unit defeated him in order to deprive Doflamingo of his supplier of SAD, the main ingredient in the Smiles production. Several major figures in the underworld, some hailing from the Kid Pirates, Big Mom Pirates, and the Beasts Pirates, witnessed Caesar Clown unleashing the deadly weapon on his own subordinates as a means of showing off its destructive potential, but when the scheme failed, his prospective buyers were left in disorder.
The defeat and kidnapping of the scientist caused a riot in the underworld and characters such as the Yonko Big Mom and Jack were informed about it. Later, Law blackmailed Doflamingo into resigning from his Shichibukai position in exchange for Caesar's return and not become a target of Kaido's fury. However, Doflamingo was able to deceive Law with false news.
Caesar Retrieval ArcEdit
The pirate, Breed, attempted to kidnap Caesar from the Straw Hat Pirates in order to produce his own SMILEs and build up a Zoan army. He was defeated by a combo attack of Luffy and the Kung-Fu Dugong, captain of the Sea Animal Pirates.
Concludes non-canon section.
Don Chinjao, Sai, and Boo of the Happo Navy competed in the Corrida Colosseum in order to investigate Doflamingo's weapons smuggling operation, which was supporting a nation in its war with the Flower Country.
Upon Doflamingo's defeat at Luffy's hands, all of his buyers were negatively impacted. A country without weapons is forced to surrender in a war. Pirates are angry about the money they have already paid to him and their inability to go to Dressrosa while an Admiral remains there. Brokers scream at the lack of SMILE and Devil Fruits to trade and one stabs the wanted posters of Luffy and Law in anger. Kaido's subordinates were seen informing him of the destruction of the SMILE Factory and the end of his professional agreement with the Donquixote Pirates since they were arrested. Additionally, Doflamingo's defeat and subsequent arrest left a massive power vacuum in the Underworld that caused many parties such as Buggy and the Pirate Dispatch Alliance scrambling to make a bid for power. Doflamingo himself stated that a global scale war between all the major powers in the world, among which are the Revolutionary Army, Yonko, Marines, Shichibukai, and The Worst Generation, is inevitable. The Revolutionary Army also gained many victories around the world due to how many countries were involved in arms dealing with Doflamingo.
While meeting up with Pekoms, the Straw Hats learned that Sanji's family, the Vinsmoke Family, is a family of killers. It is also revealed that Sanji's father is an infamous man throughout the Underworld, one capable of influencing the Marines' bounty system, and that he had recently made a political pact with the Yonko Big Mom. While disclosing more info on the Vinsmoke family, Pekoms mentioned that they command Germa 66, which Nami believed to be a mythical evil army, but which Pekoms explains is in fact a real organization which operated in the Underworld.
Whole Cake Island ArcEdit
Upon entering Big Mom's territory, Totto Land, Luffy, the Straw Hats seeking to retrieve Sanji encounter a small section of Germa 66, led by Vinsmoke Reiju and Vinsmoke Yonji. The two groups part without hostilities.
Later, another section of Germa 66, led by Vinsmoke Ichiji and Vinsmoke Niji, end a war on Broc Coli Island which had been ongoing for two years. They successfully did so within 4 hours, claiming a commission after performing their services.
- Both Donquixote Doflamingo and Smoker insinuate that Kuzan may have dealings in the underworld, though Kuzan neither confirms or denies this.