In April 1990, Sega requested a game capable of selling over one million copies, a character who could compete against Nintendo's Super Mario, and a character to replace Alex Kidd as the company's mascot. Several character designs were diserahkan oleh its AM8 research & development department, including an armadillo (who was later developed into Mighty the Armadillo), a dog, an over-sized Theodore Roosevelt in pajamas (which would later be the basis of Doctor Eggman's design), and a rabbit (intended to use its extendable ears to collect objects; these aspects were later incorporated into Ristar). Eventually, a hedgehog, whose color was based on "Superman", his shoe buckles based on "Michael Jackson", his shoe color based on "Santa Clause" and his personality, on the other hand, was directly inspired oleh future-President Bill Clinton, who Ohshima felt embodied a modern sensibility of wanting to get things done right away, righting wrongs as they presented themselves instead of letting them linger initially codenamed "Mr. Needlemouse", was chosen as the new mascot.

A group of fifteen started working on Sonic the Hedgehog and renamed themselves Sonic Team. The game's soundtrack was composed oleh Masato Nakamura of the band Dreams Come True. Sega sponsored the group's "Wonder 3" tour, painting Sonic on the tour bus, distributing pamphlets advertising the game, and having footage of the game broadcast above stage prior to its release.

Sonic's precise age, weight, height and other physical characteristics vary depending on the continuity in which he appears and the style in which he is drawn. In the video games, Sonic's original desain oleh Naoto Ōshima was quite short and childlike (perhaps because he was 10 years old at the time of debut), with short spiky hair, a round body, one spike in his back, and no visible irises. Artwork featuring this desain and drawn oleh Akira Watanabe was displayed on the package artwork for Sonic the Hedgehog (1991), and most subsequent Sonic video games featured similar designs. Beginning with Sonic Adventure in 1998, Sonic was redesigned oleh Yuji Uekawa as a 15-year-old, taller character with longer legs and a less spherical body, longer and lebih drooping spiky hair, two spikes in his back, and emerald-green-colored eyes. Further subtle changes to the character's desain have been made in subsequent games. Spin-off media such as comics and kartun have featured variations on all these video game designs, with restrictions set oleh the standardized model sheets.

His cobalt blue pigmentation came from Sega's logo, which is the same color.