This is a list of development studios owned by Sega, a Japanese video game developer and publisher based in Tokyo, Japan. Sega itself is a development studio of Sega Sammy Holdings, a company formed in 2004 after it merged with Sammy. Accompanied with the list is their history of game development. Also included are the companies that Sega has acquired over the years. For a full list of games developed and published by Sega, see List of Sega video games, List of Sega mobile games and List of Sega arcade games.

During the early 1960s, Sega had around 40 developers. One of the developers was Hisashi Suzuki, who previously was in charge of autodesign at Tokyu Kogyu Kurogane, he changed jobs to Sega in 1964, which then was called Nihon Goraku Bussan. As the company grew, Suzuki recalls about eight departments dedicated to development, which were arcades, arcade cabinets and consumer products. Sega rarely outsourced their games, much like Namco and Taito, as it was hard to find other companies that could do design, manufacturing, marketing and maintenance all at once.

Another early developer was Hideki Sato, who joined 1971. Sato has recalled that when he joined Sega, they were making pinball tables and electro-mechanical games, however still mainly sold jukeboxes. He became part of a development team that mainly had around 20 people. Sato was initially assigned to the part that made pinball tables, which were imported from America, but had modifications done to them so they would be more fun.

Sega at that time was owned by a foreign company and led by David Rosen. Rosen brought Pong from Atari to the Japanese offices, which impressed Sato. The developers quickly researched how games with TV's were made, and thus Sega quickly brought its first video game to market with Pong Tron in 1973. Hayao Nakayama, who later became president, joined Sega after the purchase of game distribution company Esco Trading. According to Sato, Nakayama was more than just a manager, he had helpful input into games like Monaco GP as well, as he firmly understood the business of games and that the development division is the most important part of a company.

Sega learned a lot about programming and software after purchasing Gremlin Industries in 1978, which was located in San Diego. It was because of this purchase that Sega began using printed circuit boards for games. Sega's first arcade board was the System 1, which debuted with Star Jacker. It was developed by Sato and was their first standardized arcade board; before then, each game had individually customized hardware. Sato remained in charge of all hardware aspects of Sega.

Home computers became an interest of Nakayama, as the MSX was becoming popular. Consequently, a small team of three people were involved in creating the SC-3000. The game capabilities of it were turned into the SG-1000, the first home console of Sega, which was made after Sega learned about Nintendo's plans to release the Famicom. At the same time the System 2 arcade hardware was developed, this time by hardware engineer Hiroshi Yagi. Yagi had first worked at Sega during the 1970s on early solid state-based pinball, but briefly left to work at Honda, before returning with the full approval of Sato. The new console Sega Mark III, called Sega Master System overseas, was made with the purpose that System 1 and 2 arcade games could easily be ported. It was thought that spreading home hardware while also developing more powerful arcade hardware would make players go to an actual arcade, and that this would create a virtuous cycle.

System 2 was also able to display multiple screens, a capability which was used in a horse racing medal game called Super Derby. This was useful for the development of the Sega Game Gear, which released in 1990. Since 1985, the Motorola 68000 was used in arcades, and it was modified to suit home consoles, which resulted in the Mega Drive in 1988, called Sega Genesis in North America when it released a year later. According to Sato this was when Sega began sharing the know-how between arcade and home hardware. Sega also increased the amount of female customers in arcades with the UFO Catcher, an improved type of crane game that existed before, and acquiring the Tetris license for arcades.

In terms of software developers, Yoji Ishii joined 1978, and was involved in sound engineering on various titles like Monaco GP and Zaxxon, before being involved in the planning section working on early arcade titles like Up'n Down, Sindbad Mystery, Flicky, Teddy Boy Blues and Fantasy Zone. He also worked with Yu Suzuki on his titles later on, and then moved on to management duties. Yu Suzuki joined in 1983, and after a year of doing chores and developing Champion Boxing, he was developing big sensory cabinet games like Hang-On, Space Harrier, OutRun and After Burner. Each took about six months. According to Hisashi Suzuki, it was the environment of being able to do everything in-house that made these kind of cabinets possible.