The series follows the adventures of a boy named Finn (Jeremy Shada) and his best friend and adoptive brother Jake (John DiMaggio)—a dog with the power to change size and shape at will.

Finn and Jake live in the post-apocalyptic Land of Ooo, where they interact with Princess Bubblegum (Hynden Walch), the Ice King (Tom Kenny), Marceline (Olivia Olson), BMO (Niki Yang), and others.

After the short became a viral hit on the Internet, Nickelodeon's executives passed on its option before Cartoon Network commissioned a full-length series from Fred Seibert and Ward, which was previewed on March 11, 2010.

[8] Adventure Time was a ratings success for Cartoon Network, with some of its episodes attracting over three million viewers, and despite being aimed primarily at children, the show has developed a following among teenagers and adults.

In an interview with Animation World Network, Ward said he strove to combine Adventure Time's subversive humor with "beautiful" moments, using Hayao Miyazaki's film My Neighbor Totoro as inspiration for the latter.

[9] Ward has also named Home Movies and Dr. Katz, Professional Therapist as influences, largely because both shows are "relaxing" and feature "conversational dialogue that feels natural [and is neither] over the top [nor] cartoony and shrill".

[15]: 32  One of the studios that Frederator approached was Cartoon Network, which was interested in producing a full series, but would commit to a deal only if Ward could prove the pilot "wasn't a one-hit wonder".

The show's lead production crew (which included Ward and McHale) was initially hesitant to bring him on board, but they were soon convinced by director Larry Leichliter, who assured them Rynda was talented and could draw in a variety of styles.

[27] After November 2014, he stopped regularly contributing to episode outlines, but still looked over stories, provided occasional input, and continued to storyboard for the series on a limited basis.

[11] Rob Sorcher said this novel approach was sanctioned because the company was dealing with "primarily visual people", and that by using storyboards the writers and artists could learn and grow "by actually doing the work".

[51][52] The series' voice actors include Jeremy Shada (Finn the Human), John DiMaggio (Jake the Dog), Tom Kenny (The Ice King), Hynden Walch (Princess Bubblegum), and Olivia Olson (Marceline the Vampire Queen).

Former storyboard artist Niki Yang voices the sentient video game console BMO in English, as well as Jake's girlfriend Lady Rainicorn in Korean.

For instance, in a panel, Muto and Kent Osborne said the Adventure Time crew often sought out actors who had had roles in the television programs Star Trek: The Next Generation and The Office to play various supporting or background characters.

[57] When Ward was developing the series' title sequences, the rough draft version consisted of quick shots and vignettes that were "just sort of crazy [and] nonsensical", which alluded to the show's theme of quirky adventures.

From there, the sequence evolved; while Ward added "silly character stuff", Patrick McHale focused his attention on the Ice King's shot and gave him a "high school [year]book" smile.

According to Ward, much of the series' music has similar "hiss and grit" because one of the show's original composers, Casey James Basichis, "lives in a pirate ship he's built inside of an apartment [and] you can hear floorboards squeak and lots of other weird sounds".

[30] Ward later described the setting as "candyland on the surface and dark underneath",[11] noting he had never intended the Mushroom War and the post-apocalyptic elements to be "hit over the head in the show".

"[95] Much of the series' LGBTQ+ representation was the result of storyboard artist Rebecca Sugar, who soon after joining the production crew "became more aware of what we're really saying by excluding [LGBTQ] characters" from children's TV—a situation which felt "more and more dire" to her.

The story was developed by Herpich, Wolfhard, Ashly Burch, showrunner Adam Muto, head writer Kent Osborne, Jack Pendarvis, Julia Pott, and series creator Pendleton Ward.

[102] In an interview with TV Guide, Muto explained that the show's writers used many of the episodes preceding the finale to conclude minor character story arcs "so we wouldn't have to cram too much in at the very end here.

Club reviewer Zack Handlen called it "a terrific show [that] fits beautifully in that gray area between kid and adult entertainment in a way that manages to satisfy both a desire for sophisticated (i.e., weird) writing and plain old silliness".

In 2013, Entertainment Weekly reviewer Darren Franich called the series "a hybrid sci-fi/fantasy/horror/musical/fairy tale, with echoes of Calvin and Hobbes, Hayao Miyazaki, Final Fantasy, Richard Linklater, Where the Wild Things Are, and the music video you made with your high school garage band".

[168] Emily Nussbaum of The New Yorker praised Adventure Time's unique approach to emotion, humor, and philosophy by likening it to "World of Warcraft as recapped by Carl Jung".

Club concluded that the show was "basically what would happen if you asked a bunch of 12-year-olds to make a cartoon, only it's the best possible version of that, like if all the 12-year-olds were super geniuses and some of them were Stan Lee and Jack Kirby and the Marx Brothers".

LeChevallier, in an otherwise largely positive review of the third season for Slant magazine, wrote that "the short-form format leaves some emotional substance to be desired", and that this was inevitable for a series with such short episodes.

[10]: 346  The newspaper Metro cited the show's frightening situations, occasional adult themes, and use of innuendo as reasons why parents might not want their young children watching it.

[192] According to Alex Heigl of People magazine, "The show's fandom is especially Internet-savvy as well, with huge communities on Reddit, Imgur and Tumblr, who swap GIFs, fan art and theories with fervent regularity".

[192] Reporter Emma-Lee Moss said, "This year's [2014] Comic-Con schedule reflected Adventure Time's growing success, with several screenings [as well as] a dramatic reading with the show's voice talent".

Moss wrote, "Looking into the crowd, it was clear that [Finn's] distinctive blue shirt and white hat were being mirrored by hundreds of Cosplayers, male and female".

[271] However, on June 12, 2024, during the Annecy Animation Festival, it was announced that an Adventure Time movie was in development, with Rebecca Sugar, Adam Muto, and Patrick McHale all involved in the project.