Jo is portrayed by G. Hannelius.
Jo is usually described as tomboyish, aggressive, devious, and manipulative. She is shown to be Gabe's "frenemy" throughout her appearances. In Boys Meet Girls, she picks on Gabe before she confesses to Teddy that she has a crush on him. She later visits the Duncans and has a playdate with Gabe. Jo's strength and aggressiveness is often demonstrated through violence; she once dislocated Gabe's shoulder while playing video games, as well as busted his lip, and gave him a black eye. In Duncans Got Talent, she agrees to help Gabe make a campaign video, but really makes the video full of lies about Gabe. In Charlie in Charge, she and Gabe are upset about a project on Hawaii they are assigned to do together, but she eventually has fun with Gabe doing the project. In Duncan vs Duncan, she and Gabe do Cotillion classes together. She also loves things that explode and it is revealed in Charlie in Charge that she is good with babies although she claims that every doll she ever had ended up without a head and she threatened Gabe to hurt him if he let anybody know.
Also, it is shown she is good at pranks. This was proven when she put some earthworms in the salad of the female teacher in Cotillion class much to Gabe's delight.
She says she likes Gabe but only a 'little'. Teddy later invited her to help her express her true feelings, but it ends up wrong when she claims Gabe cheated at a videogame then ends up dislocating his shoulder ("Boys Meet Girls").
Jo promises Gabe that she will help him run for class president. They work on the campaign video together, but when it comes in time for presentations, Gabe gets tricked by the one and only, Jo. Jo says that 'he hates babies' and much more fake facts about Gabe. He is a really caring person. People 'boo' him, but he makes a new video and shows it to the whole class. He then becomes the class president and Jo gets in trouble for sabotaging his video ("Duncan's Got Talent").
She is Gabe's partner in science class. It turns out that she is actually good with taking care of Charlie and much better than Gabe at it ("Charlie in Charge").
Jo asks Gabe to practice and be her date for Cotillion. Gabe does not agree at first, but his mom Amy forces him to be Jo's date. During the practice classes, they launch with a spoon, melon balls at each other, and then Gabe launches some at Mrs. Krump, the female instructor. During the dance practice, both of them are hesitant to hold each other close for dancing, but when they do, Jo actually likes it. Gabe is confused by Jo liking it, and tells her that he does not want to be her boyfriend. They both argue briefly and Gabe storms out of the class. Dressed up, she stops by his house asking for a corsage, and Gabe looks at her impressed. She goes to Cotillion alone, but a dressed up Gabe shows up unexpectedly, and they happily dance together and enjoy their food together.("Duncan vs. Duncan").
Jo has brown eyes and brown hair. She has tan skin and is shown to be a little short. She is very skinny but also Jo is very strong.
- Main article: Jo and Gabe's Relationship
Jo and Gabe's relationship is very complex. Jo couldn't show her emotions throughly to him, frustrating her and always ended up hurting him. ("Boys Meet Girls"). She is in denial at first, but then admits it. Gabe feels the same way. In Duncan vs. Duncan Jo asked Gabe to join her for cotillion, as her date. In Disney's promo, they narrator says "Has Gabe found his perfect match?" and the answer is probably yes, but in an interview asking Bradley, "Will Gabe and Jo ever kiss?" They did but not on tape! He thinks they will never get that close, but still are good friends. It is possible that she is the mother of Gabe's son, Gabe Duncan Jr. in the future.
- She has a crush on Gabe Duncan. Gabe also has romantic feelings for her as well as they claim just a little bit.
- As revealed in "Boys Meet Girls", she says she likes monster trucks, mixed martial arts and dolls.
- She likes it dirty.
- "Duncan vs. Duncan" (Last appearance)