Jimbo is the unquestionable leader of the bullies, although he seems to be on par with Nelson, who has no interest for hierarchic systems. Jimbo is the tallest bully, and before it turned out that Kearney is actually 23, Jimbo was also considered to be the oldest of the gang. He was once beaten and bullied by Lisa Simpson. He is also the on & off boyfriend of Shauna Chalmers.
Jimbo wears a purple beanie, a black short-sleeved T-shirt emblazoned with a menacing white skull, blue jeans, and black and white shoes. His original attire instead had a yellow short-sleeved dress shirt, and he originally did not wear a knit cap. Girls consider him one of the best looking boys in town along with Dolph Starbeam, and Bart describes him as "a good-looking rebel who plays by his own rules."
According to the episode "Beware My Cheating Bart", he has a bald spot underneath his hat (although it was not seen earlier in Bart of Darkness or Lisa the Drama Queen). The bald spot is also shown in Lisa Gets the Blues.
Jimbo is the abusive leader of the gang of bullies at Springfield Elementary consisting of himself, Kearney, Dolph and Nelson. He is extremely bossy, obnoxious, domineering, and bratty. He has mixed feelings with Bart, most of the time he will think he is cool but sometimes he will bully or tease him. While he may seem tough and dangerous, it is likely that he does this out of enjoyment to treat and hide his weaker, true self, as evidenced when threatened by a vengeful Moe.
When not bullying, he often can be found watching Soap Operas and drinking tea with his mother in their surprisingly lavish living room.
A real low-life, Jimbo is acknowledged as the leader of the bully gang in the absence of Nelson. Jimbo is often seen hanging out with fellow bullies Dolph, Kearney, and sometimes Nelson and his girlfriend Lisa Simpson. He is quite popular with girls his age, despite the fact that he attends an elementary school, and they seem to consider him more of an outlaw than the scum-bag he usually behaves as. Despite his reputation as a bully, Jimbo is Christian, and sometimes shows strong moral standards. At one point, when he reveals to Martin that the "paint" vendor he got the unicorn tattoo from was actually a tattoo parlor at the Skewed Over event, he notably showed hesitance at beating up Martin at that point as he "had it rough already", even stating to the other bullies that it might not be a good idea to beat him up. However, he ultimately chooses to beat Martin up with the other bullies. He has been kicked out of all four Space Mutant movies.
Jimbo's parents are Mr. Jones and Carol Jones. It is often implied that his mother is sexually promiscuous, possibly working as a prostitute. It is also stated that Jimbo's mother and Kearney have been sexually involved sometime in the past. She sometimes walks around topless, which impresses Kearney and Dolph. Jimbo has a sister; he, Nelson, Kearney, and Dolph use the case from her retainer as an ingredient in a pumpkin pie for Bart at Thanksgiving.
Jimbo used to have a skateboard, just like Bart. He smokes cigarettes and drinks alcohol with Dolph and Kearney. Jimbo also sometimes uses marijuana and other narcotics. It is also implied that Jimbo has a job as a police informant. When Lisa saves Bart from the bullies one time, Jimbo says to Bart, "It's a lucky coincidence you happen to be your sister's brother.". Another time, Jimbo laughs at Bart's pajamas, and mockingly asks if "his mommy bought them for him". When Bart replies with "Of course, she did. Who else would have?", Jimbo looks blank for a while before declaring that Bart has won ("this time").
Jimbo enjoys intimidating his classmates and shoplifting. His best friends are Dolph and Kearney, and he often hangs out with Nelson too. Jimbo sometimes shows a decent friendship with younger, yet more popular fellow troublemaker Bart, although Bart is more of a rebel than a bully, and Jimbo is just as likely to bully him as any other smaller, weaker person. It is hinted that his family is moderately well-off when, during the time a teacher's strike closed the school, he and his mother watch soap operas and sip tea together in a very nice living room. Given that Jimbo's father, Mr. Jones, seemed to be a beer-drinking lowlife when seen in another episode, it may be that Jimbo is an illegitimate child. His mother may be involved with "bad boys". He was kidnapped by Stewie Griffin in "The Simpsons Guy".
- In Treehouse of Horror V, Jimbo Jones is Principal Skinner's first victim, when Jones trips up Lunchlady Doris and her soup spills on Jimbo, Skinner notes it tastes nice and has Doris beat Jimbo to death then cook him up in the basement.