Netflix has yet to announce if The Umbrella Academy will return for Season 3, but it seems likely that the show will be back. Not only is it reportedly one of the streaming site's most popular shows, it's based on Gerard Way's comic book series of the same name, which currently has three volumes: Apocalypse Suite, Dallas, and Hotel Oblivion. So there's plenty of material to build on in another season. (Warning: major comic book spoilers ahead).
In Volume 3, the Hargreeves siblings discover that, before his death, their father created an off-world prison to house his enemies called Hotel Oblivion. After being set free by a man named Mr. Perseus, the villains (including the team's biggest nemesis, Dr. Terminal) are unleashed on Earth and begin wreaking havoc on the Umbrella Academy as well as the world at large. But just when the siblings think all hope is lost, a new group of heroes arrive to save the day. They too wear special costumes and possess supernatural abilities, making it likely that they're among the other 36 gifted babies who were born on Oct. 1, 1989.
That leaves plenty of storyline for a potential Season 3 to explore, and there's also a fourth volume of the comics currently in development. “The goal for us is to stay ahead of the show,” comics creator Gerard Way told IndieWire shortly after Season 1 premiered.
Way also spoke with Collider in March 2019, revealing that he plans to write eight volumes of the Umbrella Academy comics in total.
“What I did for Steve Blackman and the writers in that first writer's room was to create an 18-page document that laid everything out. Even of the graphic novels that haven’t come out yet, which should equal eight when we’re all done,” Way explained. “So I gave them the blueprint for what happens, because you do want to seed certain things in there for future series and the hope is that it’s a success so that you do a lot more of these.”
With that in mind, it seems like only a matter of time until Netflix announces Season 3.