Big Mom often drools large quantities of saliva when talking. When in her frequent fits of rage from not having a certain food at her direct disposal, her pupils take on a spiral appearance.
Big Mom wears a large pink bicorne hat bearing a Jolly Roger on the front. She has worn two versions: the first design consisted of a standard skull with crossbones behind it, as well as large flame-like patterns to the sides, whereas the current version has two crossed sabers instead of crossbones, possesses smaller lateral flame patterns, and is imbued with a fragment of someone's soul, causing its skull to change expressions and talk to Big Mom; on its top, the hat is edged with a thick yellow streak, it has a strip snap-fastened to it, and beneath it is a light, polka-dotted bandana fastened around Big Mom's head. Big Mom also dons a pink dress with red polka dots and white ruffles on its neckline and hemline, with a wide, rippling white cape attached to its back that falls to the ground. The outfit is completed with dark blue high heels, one turquoise pearl wristband on either wrist, and golden, jeweled rings on all her fingers.
Big Mom loves to eat sweets above all else and has all the islands under her external protection pay her with metric tons of whatever kind of confectionery they can produce. She is obsessed with sweets to the point of destroying entire countries for failing to deliver them. In fact, she loves her sweets so much that her subordinates or her territory holds less importance compared to it. Despite this, she does not lose control when Luffy claimed to have eaten all the candy that Fishman Island owed her; instead, she correctly deduced that he was lying in order to protect Fishman Island.
In addition, Big Mom has a peculiar eating disorder where, at seemingly random times, she becomes fixated on a specific food item and goes on a crazed rampage in search of what she wants to eat. While in this state, she will kill and destroy everything in her path including her castle, her subordinates, and even her own children until she receives the food she wants. When rampaging, her pupils become crazed and swirly. Once her cravings are satiated, she becomes more affable and retains no memory of her actions during her rampage. When calm and thinking rationally, Big Mom possesses a rather businesslike mindset and strongly believes that a pirate must accept no compromises or delays for something they want. Pappug thinks she is protecting Fishman Island with a business perspective since the deals made with the candy qualify as racketeering, though she prioritizes sweets over money and treasure; she initially refused an alternative payment of treasure when Fishman Island's monthly candy tribute could not be met, only accepting out of amusement once Monkey D. Luffy openly stood up to and defied her over the payment.
This even extends to her allies and crew; should one of them choose to leave her crew or cut ties with her, Big Mom forces them to give up something precious to them as compensation, uncaring of their reason for leaving to begin with. Similarly, she expects all citizens of Totto Land to sacrifice portions of their lifespan as the price of residing in her country, further illustrating her desire to be compensated for everything she provides.
Big Mom is also selfish and obsessed with power; her marriage of Pudding to Sanji is solely for the sake of gaining access to the advanced combat technology of Germa 66,, a process which she is willing to repeat with all her children in order to strengthen her own crew. When a marriage is threatened or annulled, Big Mom will become incredibly angry at the people responsible and aim to kill them mercilessly, even if they are her own children; the larger the power she fails to gain, the angrier she will become. This lust for power stems from her desire to overthrow the other Yonko and ultimately become the Pirate King. Big Mom has some interest in the Poneglyphs despite being unable to read them.
An extremely ruthless woman, Big Mom is infamous for destroying countries over slight infractions (though most often when they fail to make their monthly payment of sweets), disregarding any and all reasons for the failure while rationalizing that she despises people unable to keep their promises. Generally, there are two things she dislikes: bitter treats, and invitees not showing up for her tea party. Demonstrating herself to be very brutal, she does not forgive those who refuse invitations to her tea parties, and she will kill people precious to the absentee as a "present".
When it comes to dealing with enemy pirate crews, Big Mom specifically instructs her children and other subordinates to give her enemies false hope before crushing their spirits as brutally as possible. Big Mom is highly confident in her power and fails to see most crews as even a remote threat due to her and her crew's capabilities. Big Mom's malevolence extends to encouraging violent behavior in her children; when Anana wanted knives to cut up her stuffed animal, Big Mom immediately asked two of her sons to bring knives to her. Despite her ruthless and vindictive nature, Big Mom can be compliant and forgiving when necessary, as she granted Sanji's request to spare the Straw Hat Pirates as long as his wedding proceeds smoothly. However, if the other party fails to uphold or goes directly against the agreement, Big Mom will display immense rage and will not hesitate to inflict the worst punishment upon them.
Big Mom also desires to create a nation where all races can happily live together due to wanting a "family" comprised of individuals of all races that she can dine with at eye level with via Caesar Clown's gigantification research. Big Mom is so dedicated to this dream that she is willing to invest massive amounts of money in Caesar's research, even building a working replica of Punk Hazard's laboratory in the event that it was destroyed and offering more financial support after Caesar is brought to her with no results; however, her fixation on this dream rendered her oblivious to how Caesar was simply embezzling money from her for his own indulgences. However, for reasons unknown, no giants live in Totto Land, and Big Mom briefly became enraged when Vinsmoke Judge mentioned them. Her obsession with diversity is not just limited towards her family; she also wishes to collect rare and unique animals for her own pleasure, as explained by her eighth daughter who claims that Big Mom would not be satisfied with just having all the races of the world for herself. She is very jolly when in a good mood and enjoys celebrating the fulfillment of her ambitions with song and dance, but her cheerfulness betrays an underlying sense of malice, as she is completely unfazed by the violence necessary to achieve her goals. She is also willing to completely disregard her children's wishes on marriage for the sole sake of strengthening her crew. She seems to recognize others by their lineage first and foremost, as she often speaks of others in terms of their relation to their parents and grandparents.
She refers to herself with "ore" (おれ?), a very masculine way of saying "I", instead of the gender-neutral "watashi" (私?) that most other females use.
Like many others, Big Mom has a distinct style of laughing: "Mamamama". However, she has also laughed in a normal "Hahahahahaha" style (occasionally with a drawn-out "Haaaaaaaa" at the beginning,) and has even combined it with her unique laughter in the form of "Haaaaaahahamamamama".