Oobi is a curious puppet with an eye for adventure. He explores the world around him in small steps and is always eager to learn something new. Oobi acts as a role model to his younger sister, Uma, who often looks to him for guidance. He has a good-natured demeanor and a keen sense of loyalty to his friends. His quiet, self-conscious nature is often contrasted with Uma and Kako's goofiness and slight arrogance. His favorite color is blue, and most of his belongings have a blue color scheme to set them apart from the other characters' things.
Oobi is closest with his sister Uma and grandfather Grampu. His best friend is his next-door neighbor Kako, who visits Oobi's house so much that he is practically another member of the family. Oobi's friendship with Kako has lasted since they were very young. They have a lot of the same interests, like playing T-ball and taking care of pets. However, their personalities are drastically different and balance each other out. Kako is jokey, energetic, and somewhat conceited while Oobi is more reserved and thoughtful.
Oobi is also friends with Frieda the Foot, a girl who happens to be a foot puppet instead of a hand. When he first met Frieda, Oobi was instantly smitten with her but thought they couldn't play together because they look and act differently. Luckily, Grampu helped him realize that differences are good and people come in many shapes and sizes; he has been a close friend of Frieda ever since.
A recurring element in the series is Oobi's aspiration to become a piano player. He regularly takes piano lessons from Inka, an elderly woman who is dating Grampu. Being a hand, Oobi needs to focus all of his energy on the music when he plays the piano; after all, he uses his entire body to touch the keys. He takes great pride in his ability to master simple tunes, but tends to get nervous while performing in front of others.
In addition to taking piano lessons, Oobi is also part of the community center singing group. He and Kako visit the center every week to take singing lessons from Maestru, the local voice teacher and part-time conductor. Maestru was not very fond of Oobi or Kako when they first met. He knew the boys had a talent for singing when they put their minds to it, but they preferred to sing their own songs rather than perform as part of the group. Luckily, after some practice and a short talk about what it means to be part of a team, Oobi and Kako learned how to sing in unison and became official members of the singing group.
Oobi's favorite toy and prized possession is a red toy racecar, modeled after a 1973 Ford Mustang. Although he loves playing with it, he obsesses over keeping it in perfect condition, treating it more like a collectible than a toy. He is always hesitant to let anyone else touch his car, out of fear that they'll somehow break it. On the one occasion that Oobi let Uma play with the car, she accidentally broke a loose wheel off and ended up destroying the whole thing while trying to fix it. Luckily, Grampu was able to fully repair the toy with the kids' help, and Uma even fixed its squeaky wheel with some oil.
At the end of every episode, Oobi waves goodbye to the viewers while using his catchphrase: "Oobi, you, friends!" Even when he is not the main focus of an episode, Oobi shows up at the end to recite this line; for example, "Uma Preschool!" features him greeting Uma at the end simply to say it and wave goodbye to the audience. There are occasionally meta-references within the show about his persistent use of the phrase, including a scene in "Uma Dreams!" that reveals he even says it in his sleep.
Being the main character, Oobi was the first puppet created for the show. From the beginning, he was meant to resemble the simplest kind of hand puppet imaginable, with his signature acrylic eyes being his only accessory. Series creator Josh Selig said in 2004 that he experimented with many different names while developing the character. His first choice for Oobi's name was "Pipo". He had to choose a different name after he was informed that Pipo was already trademarked by an Italian clothing company. He still wanted "a name that wasn't like any other name" and "didn't want to name Oobi after a real child, since he's kind of his own species." He eventually settled on Oobi because the double O's mirror Oobi's iconic eyeballs.
Oobi's performer, Tim Lagasse, is an established puppeteer for Sesame Workshop. He was chosen to play Oobi because of his previous work as a bare-handed puppeteer on A Show of Hands. This was a series of short films that Lagasse wrote and directed for Nickelodeon. Each short featured Lagasse and several other puppeteers performing simple, humorous skits with their hands. They focused on the visual illusions that can be created with hands' gestures and shadows. Many of the techniques that Lagasse used to convey expressions through hand motions in the films were carried over to Oobi.
In an interview with the Newsweek magazine, Josh Selig mentioned that Lagasse had to shave his arm regularly while working on Oobi so that his character would not look like an adult. Tim and the other cast members were paid to visit a manicurist and get their nails touched up every week during production. On his website, Lagasse has mentioned that Oobi "is probably the most unique thing I have ever done."
Oobi has fair skin and pink fingernails. His eyes are dark brown in the shorts and hazel in the full-length episodes. Four fingers act as Oobi's upper lip, while his thumb acts as his lower lip. Unlike most of the other puppets, he only wears accessories or clothing on special occasions.
Three pairs of acrylic puppet eyes were used for Oobi throughout the show's run: a brown pair in the shorts, and two separate pairs of hazel eyes for seasons one and two. With each new pair, Oobi's eyes became progressively lighter in color.