Development
Nefcy said she originally created Star as a girl who wanted to be a magical girl like Sailor Moon, and Marco as a boy who was obsessed with Dragon Ball Z and karate; they would be enemies instead of friends. In this earlier version, Star did not have any actual magical powers; she instead would approach and solve problems primarily through the force of her determination alone. Nefcy began pitching the show to Cartoon Network during the time when she was in her third year of college, when the network was actively soliciting the creation of pilots for The Cartoonstitute. However, the network did not green light her vision for the show and was not made. Nefcy originally placed Star in the fourth grade, reflecting on a time in her own childhood when she held a self-described obsession with the animated series Sailor Moon. However, Nefcy later adjusted the character's age to fourteen during the time she made her series proposition to Disney rather than Cartoon Network originally. An executive at that time made the suggestion for Star to have actual magical powers. Nefcy worked this concept into the show's current iteration, along with different dimensions as locations, the foreign exchange student framing device, and the consequences of Star's royal birthright. Nefcy said that the overall concept has evolved over about six years.
In addition to Sailor Moon and Dragon Ball Z, Nefcy has said that she had heavy influence in her youth from the Japanese anime series Magic Knight Rayearth, Revolutionary Girl Utena and Unico, the last of which featured a blue unicorn. She also cited shows unrelated to Japanese animation such as Buffy the Vampire Slayer, and was influenced by independent comic series such as Scott Pilgrim and The Dungeon. With regards to the development of more strong female characters, Nefcy said that she "looked at TV over the years and I have had to go to Japan when I was younger to find the cartoons that had the characters that I wanted to see. It was always a question of 'Well, why isn't that on TV in the U.S.?'"
One of the concepts she likes about the show is that it does not make high school the most important experience for teenagers. She also likes that Star does her own thing instead of being concerned about fitting in. Nefcy did not want the gimmick about keeping the magic powers a secret from others as typical of magical girl shows, so she had the students already know about it and Marco's parents as well. She also portrays Star as not really a superhero as she does not specifically go after super-villains except when they attack her, and that she does not really save people. Nefcy said that the episodes balance comedy and drama: "we really want our characters to feel like teenagers and have them going through the normal emotions that teenagers go through, but in this magical setting."
Storyboarding and design were done in Los Angeles. In describing the process, Nefcy said that the show is storyboard-driven, with each episode mapped out by the storyboard artists. The storyboarders also do the writing, taking a two-page outline and turning it into a full script. A storyboard for 11 minutes would require about 2,000 drawings to be done in a six-week period. After pre-production in the US, the first season animation was done at Mercury Filmworks in Ottawa, Canada. Mercury had also done Wander Over Yonder and the Mickey Mouse series. For the rest of the first season, the animation was done at Toon City in Manila, Philippines. The rest of the series (seasons 2–4) was animated by Sugarcube and Rough Draft Studios, both located in South Korea.
The theme song was done by Brad Breeck, who also did Gravity Falls' opening theme. Nefcy said, "when we were listening to it we didn't know, because we just listened blind". Brian Kim was chosen among a group of about ten people as the show's composer. Kim describes the music for each dimension as having a different sound and relating it to indie rock in Los Angeles.
The show was initially scheduled to premiere on Disney Channel after being greenlit in March 2013, for a premiere in the fall of 2014, before being switched over to Disney XD. However, on February 23, 2018, it was announced that the show would be moving to Disney Channel for its fourth season. On February 7, 2019, it was announced that the fourth season would be its last.
