Oseman published two ebook novellas based on characters from Solitaire, titled Nick and Charlie (July 2015) and This Winter (November 2015). Both were published by Harper Collins Children's Books.

In 2016 she published her second novel, Radio Silence. The novel follows Frances Janvier, a high-achiever whose life revolves around her admission to Cambridge, who meets the shy creator behind her favourite podcast, Aled Last. Themes such as academic pressures and LGBT+ relationships and identities are central to the novel. Oseman has been open in interviews about how Frances' experience in Radio Silence was similar to her own school pressure and a later disillusionment with academia following her education at Durham University. This novel has been praised for representing characters of various ethnicities, genders and sexualities. Oseman has often written about the importance of writing diversely on her blog and has spoken about the lack of diversity in Solitare in interviews. The novel won the 2017 Silver inky akward for young adult literature.

Her third book, entitled I Was Born For This, was published in May 2018. It follows the story of Fereshteh "Angel" Rahimi and Jimmy Kaga-Ricci. The story is about a band called The Ark and their fandom, with a particular focus on fandom among teenagers.One reviewer said that a message in the book was that you can be a part of a fandom, but you have to make sure you don't lose yourself in it, and being an extreme fan can prevent those in the spotlight from feeling like they can be themselves.

She is also the author/artist of the web comic Heartstopper,which follows the romantic relationship between Charlie Spring (brother of Tori Spring) and Nick Nelson, both of whom are characters featured in Solitaire. The first four volumes of the comic have been acquired by Hachette Children's Group.Volume one was published in February 2017, volume two in July 2019, volume three in February 2020.

Oseman's novels have been praised for being "relatable" and realistic in regards to their portrayal of contemporary teenage life. Her first book Solitaire was particularly praised due to her young age at the time of the publishing deal, which contributed to a BBC Breakfast interview on 22 July 2014.

In 2018, to celebrate the release of her third Young Adult novel, I Was Born For This, all of Alice's published books received new, matching covers. The re-designed covers were released in May, along with the new book.

In July 2020, Oseman published her fourth novel Loveless, which is based on her own experiences in university.^[

Netflix optioned the rights to Heartstopper in 2020. On 20 January 2021, it was revealed that a live-action television adaptation of Heartstopper was to be adapted with Netflix, with Oseman writing the script and Euros Lyn directing. The series will be produced by See-Saw Films.The executive producer is Patrick Walters of See-Saw Films ^[26] Kit Connor and Joe Locke will star as Nick and Charlie respectively.^[