Jimmy is an insecure child with a propensity to cry. He wishes to become famous, and is most often seen spending most of his time with Sarah. Jimmy is accident-prone (usually seen sporting many bandages and band-aids), and is the weakest child in the Cul-de-Sac (as evidenced in "Cry Ed," when his foot broke after a clothes-peg bounced onto it). Though Jimmy has a cowardly and delicate personality, he wishes to be strong and muscular. He can be crafty when motivated, and twice formulated scams that were very successful - even getting back at the Eds with one particularly cunning scheme. Jimmy has shown how deeply attached he is to Sarah when someone tries to take her away from him. Jimmy shows excellent cooking skills in some episodes, using his "Easy-Bake"-style oven to make soufflés and, on one occasion, cookies that were shaped like sailors.
During an interview  with creator Danny Antonucci, when questioned about Jimmy's background he went on to say:
|“||Jimmy's based on my cousin. Precious, delicate and spoiled rotten, he was always more comfortable hanging out amongst the girls than us boys and so of course we would tease him and do horrible things to him. His ears went bright red when he got upset.|
Jimmy may seem weak and girly, and enjoy dolls more than monster trucks, but he has a darker side in addition to his more commonly seen infantile persona. When the show first started, Jimmy was very accident prone and was teased a lot, especially by Eddy and Kevin. He was nervous in most every situation, especially those which did not fit into his and Sarah's world of dolls and tea parties. Over time, however, he becomes a mischievous, sneaky little kid who frames the Eds and learns to scam people. There is still a lot of teasing going on in his life, though, and he is still in most cases a wimp.
In earlier episodes, Jimmy can usually be seen playing with Sarah, her telling him what to do and when to do it and watching over him like he is her son or, perhaps, a little brother. This setup seems to work well for them both. Jimmy is happy with his cooking, gardening, and dolls, as well as the bossing around from Sarah that comes with the territory. He puts up with Sarah's bossiness because anyone who wants to get at Jimmy must go through his redheaded bodyguard. In addition to protecting him in the physical sense, Sarah also protects Jimmy emotionally. When Rolf insults Jimmy’s quiche in "Pop Goes the Ed" by stating that it is a cursed food and has in turn cursed the party, Sarah comforts the crying Jimmy and says that she like to eat quiche, which seems to be all that matters to Jimmy.
Again in the Season 2 finale "Cry Ed," it's Sarah who is constantly on hand to put the accident-prone Jimmy back together, while drawing the other kids' sympathy away from attention-seeking Eddy. He does show that he has an angry side on occasion, though. In Season 1's "An Ed Too Many," he takes out his frustration at Sarah's apparent infidelity first on a teddy bear, then on Jonny, and finally on a gloating Eddy. Although these attempts at releasing his rage are futile (except when practiced on the bear), they do show that Sarah to some extent acts as a buffer, keeping him from being violent. In Season 3's "Wish You Were Ed," Sarah pushes him into a rage by constantly complaining about his driving skills, and this shows that even she is not immune to his anger. As the show progresses, it seems that Jimmy is much tougher than he would appear after a cursory glance.
Season 2 seems to be the real turning point for him. This is perhaps a direct result of being turned into Eddy's reluctant protege in "Ed in a Halfshell." This is disputable, however, as the harder edge revealed more explicitly in later seasons starts developing even before Season 2's 22nd episode. He begins to display a sharper attitude, a sharper tongue, and reveals himself to be a natural when it comes to fleecing the masses, turning into a ruthless money-hungry businessman with a success rate that Eddy can only dream about. From this point on, though he is still most comfortable being passive, Jimmy continually proves that he can hold his own when he has to. In fact, he displays a rare and somewhat unnerving talent for behind-the-scenes work–in "If It Smells Like an Ed" he sets the Eds up three times: once at the start, framing them for ruining Friendship Day; once near the end, where he makes the kids believe the Eds committed crimes against Jonny; and as a finale, he has the Eds dragged off by the Kankers. He does all this simply because Eddy humiliated him in front of the other kids by giving him a wedgie. It is apparent after viewing this episode that he's quite dangerous.
Jimmy doesn't really know what to make of the Eds and their scheming. He wants to trust them, and most of all, see good in them. You'd think Jimmy would learn his lesson after falling for each successive scam, but he never does. Worse, if Eddy caters to and strokes Jimmy's ego, it causes him to be tricked even more easily. This is Jimmy's greatest weakness, and Eddy's biggest advantage over him. Blinded by his quest for respect, fame and glory, in love with the concept of being loved, he's prepared to go to any length, even if it means ditching Sarah and her good advice. One episode that proves this is Season 4's "One Size Fits Ed," where Jimmy allows Eddy to force-feed him megatons of peaches and cream under the premise of becoming famous. He also leaves Sarah with very few qualms in "Hands Across Ed."
Jimmy is interested in fashion and art. Anything to do with the arts, be it painting, directing, or performing in front of an audience leaves him positively alight with anticipation. Jimmy's highly evident artistic talent allows him further scope to gain attention (often, like Eddy, to the point of milking it.) He revels in his own extreme delicacy, for he believes nobody suffers like an artist. This has mixed results, naturally. It's a wonderful thing that your artistic soul, burdened by the misery of trials such as waxy build up on fruit, and your cookies getting burned, means you're never short of sympathy from your friends. This can lead to being spurned when they get sick of hearing about this, however, although this does not often happen.
Jimmy is also very accident-prone. While he is certainly most noted for his fluffy hairdo and that distinctive retainer, he's also likely to be seen sporting a myriad assortment of Band-aids, bandages, and plaster casts. Delicate and fragile to the extreme, it seems there's always something wrong with Jimmy, be it a bandaged nose, a splinted arm, or a simple bump on the head. He gets seasick, rubber tires give him a rash, hopscotch makes him dizzy, he doesn't like being alone, doesn't like strange foods, gets freaked out by camera flashes, bad breath makes him faint, scary stories frighten the jujubes out of him, and Eddy makes him very nervous. Whenever he's not ailed physically, it seems that something's wrong either mentally or emotionally.
Jimmy gets on well with all the cul-de-sac kids, although he's wary of loud-mouth Kevin as he often makes fun of him for being a weakling. He knows nobody's really going to get him, because he has a fiercely loyal bodyguard who will spring to his defense at the first whimper. He does join in with group games and Urban Rangers activities, but he's happiest (and safest) when he's with Sarah. Sarah may tell him what to do, but she doesn't tell him what to be, and so he's free to talk about tea sets, curtains, the latest fashions, or offer to style Sarah's hair without fear of rebuke or mockery.
Relationship with The Eds
For the entire series (except in dreams, and flashbacks taking place before his accident), Jimmy wears a retainer to reset his teeth. This is due to a scam gone awry, when Jimmy bit into a bowling pin that Eddy had disguised as a pastry horn (revealed in a flashback in"Every Which Way But Ed"). Even though Eddy has shown a low regard for him (and vice versa), Eddy feels that Jimmy is a rising star, and tries to take advantage of this when he can. One specific example is when Eddy teaches Jimmy how to run scams in"Ed in a Halfshell."
Ed has a strong bond with Jimmy. Even though it usually isn't beneficial (to Jimmy or Ed), Jimmy often likes to imitate Ed and do the foolish things Ed does. He also appears to be friendly with Edd, as they both are weak, fear gym class, and share similar interests. He briefly joined the Safety Club run by Edd, but quit when it was proven ineffective, and replaced it with his Owie Go Kapowee Club. Even at the end of the Ed, Edd n Eddy's Big Picture Show, he helped straighten Edd's tie as a kind gesture. The only major conflict between the two was in"An Ed Too Many," when Jimmy was jealous of Edd and Sarah.
Edd and Jimmy also share a special bond over the Baby Blue Gym Sock. Jimmy is the first one after Edd to notice the flower in "An Ed Too Many." After learning that Edd had cross-pollinated a Baby Blue Gym Sock and a rose in "A Fistful of Ed" he remarks that only, "Hands as gentle as hummingbirds' wings could have done such a thing" and subsequently reverses his recently gained opinion of Edd as a tough guy.
Jimmy wears a cyan colored sweater, white pants, black belt, dark brown shoes with black soles (sometimes white in Season 5), and a brace ring. In winter he wears a medium blue sweater and a dark magenta button-up fur coat. Jimmy has fair skin, magenta eyes, and a purple tongue like Rolf and Sarah.
Old Jimmy, seen in "Take This Ed and Shove It," still has a retainer, though it is bent and dented up, and looks like it will come apart at any moment (most likely implying that it is the same retainer he wore as a child). He and Sarah have remained best friends for 90 years, but it remains unknown if a romantic relationship developed between the two of them. He and Old Sarah now do a lot of knitting. He still doesn't like Eddy as he called Eddy "poopy pants." Jimmy has a bandage on the side of his head, implying that he still gets injured frequently.
- Jimmy: "Someone get me off this Merry-Go-Round called life!."
"Avast Ye Eds"
- Jimmy: (after seeing Edd in a gas mask) "GYM TEACHER!"
"High Heeled Ed"
- It is said that Jimmy's father forces him to practice hockey.
- However, Jimmy may have lied about this as he was in need of a quick reason to be in possession of a hockey stick in "If It Smells Like an Ed."
- In "Boys Will Be Eds," Jimmy admits that he can play the xylophone.
- Kevin calls him "Fluffy," referencing his hairstyle.
- In "Hand Me Down Ed," it was discovered that his opposite personality is a musclebound, macho tough guy, the same personality that he assumed after being hypnotized in "Look Into My Eds."
- In a baked goods scam from at least a year in the past, Jimmy ruined his teeth by biting into a fake cream horn which was actually a bowling pin. It can be assumed that Jimmy ruined his teeth permanently.
- However, his retainer is destroyed a few times so that could make his teeth worse.
- In "Ed in a Halfshell," Rolf asks Jimmy if he realizes that his "hair resembles the backside of a chicken."
- According to "Who, What, Where, Ed," Jimmy likes plums and clams, since he was going to trade a giant teddy bear and paint for those two items.
- In "If It Smells Like an Ed," it is revealed Jimmy has a dark side to his personality which will awaken if Jimmy is made fun of continuously by other people.
- Danny Antonucci said that Jimmy was based on his cousin in the Ed, Edd n Eddy Season 2 DVD.
- Jimmy is a member of the Urban Rangers.
- Jimmy's hair is exactly the same color as his skin.
- Although Jimmy is a nice person, the following can make him very angry or crazy:
- When he is given a wedgie and everyone laughs continuously at him to no end (as seen in "If It Smells Like an Ed").
- When another male tries to romance Sarah (as seen in "An Ed Too Many").
- When he is pounded on too much (as shown in "A Fistful of Ed").
- Running Gag: Jimmy having some sort of injury, band-aid or cast on him throughout almost every episode.
- In the game Cartoon Network Universe: FusionFall, Jimmy and the other kids are all missing.
- It is possible Jimmy has relatives or friends from Nebraska because of the postcard he received in "The Eds are Coming."
- In "The Eds are Coming," it is revealed that eating bon-bons before bed gives Jimmy nightmares.
- In "A Fistful of Ed," Jimmy is shown to become super strong if he gets angry to the point of going berserk.
- Jimmy's voice was deeper in the early episodes of the show, but later his voice changed to a more childish voice. His personality seems to have changed to be even more childish.
- Jimmy is the only character to wear different pajamas. He switches from a baby blue footed pajama that zips up in the back, to orange footed pajamas and then to pink footed pajamas.
- During the younger Eds' flashbacks in "Every Which Way But Ed," Jimmy's house was under construction, hinting that Jimmy is not originally from Peach Creek.
- However, since Jimmy is considerably younger than the Eds, it's more likely he wasn't yet born at the time.