Older's debut novelHalf-Resurrection Blues was published by Penguin Books in the first week of 2015. By the end of January, the production company of Anika Noni Rose had optioned the television and film rights to the novels, in addition to the rights of the following two novels in the series. Also in 2015 Older published his second book, a young adult novel entitled Shadowshaper about a young Afro-Latina girl named Sierra who discovers her family's history of supernatural powers and her ability to interact with the spirit world. Until 2014, Older worked as an emergency medical technician in New York City, writing mostly at night. Older has said that he sees himself as an outsider to the publishing and literary scene, saying "I entered the writing work clearly and strategically to do this thing, to write these books, to get them into the world and fuck with people, and to generally fuck shit up." Older has been critical of works that fail to include racial diversity. While he admires The Hunger Games series of novels, he was disappointed in the casting of the film series based on them, writing that the "whitewashing of Katniss was a tremendously unimaginative and useless act." Older has also been critical of "the popular surge of YA dystopias that followed in the wake of the HG trilogy," calling it "wildly undiverse." He attributes this lack of diversity to a "phenomenal lack of imagination" on the part of the authors, and a laziness, he feels, designed to keep some people out of the picture, saying: "To be able to figure out all these quirky things about what you imagine the future will be like, and not somehow have any folks of color doing anything heroic or worthwhile in it, what happened?" In 2018 Older released his first Star Wars novel Last Shot, which serves as a tie-in to . It stars Han Solo and Lando Calrissian and takes place between Return of the Jedi and The Force Awakens with flashback settings before and after Solo.
In August 2014, Older started a petition to change the World Fantasy Award statuette from a bust of H. P. Lovecraft to one of African-American author Octavia Butler, on account of Lovecraft's racism, and concerns that it would be disrespectful to recipients, in particular those belonging to non-white ethnicities that Lovecraft held in particular contempt. Kevin J. Maroney, editor of The New York Review of Science Fiction, also supported the call for the WFA to be changed from Lovecraft's face, suggesting it be replaced with a symbol representing the fantasy genre. Maroney argued this should be done "not out of disrespect for Lovecraft as a writer or as a central figure in fantasy, but as a courtesy to generations of writers whom the WFA hopes to honor." In November 2015 it was announced that the World Fantasy Award trophy would no longer be modelled on H. P. Lovecraft, following the 2014 campaign that called the author out as an "avowed racist" with "hideous opinions". Older expressed delight at the news and posted on his Twitter account, "They just announced the World Fantasy Award will no longer be HP Lovecraft. We did it. You did it. It's done. Yessssssss," Older tweeted. Older later told The Guardian newspaper by email, "If fantasy as a genre truly wants to embrace all of its fans, and I believe it does, we can't keep lionising a man who used literature as a weapon against entire races. Writers of color have always had to struggle with the question of how to love a genre that seems so intent on proving it doesn't love us back. We raised our voices collectively, en masse, and the World Fantasy folks heard us. Today, fantasy is a better, more inclusive, and stronger genre because of it."
