Joshua Fine and other creators of the series were initially developing a Hulk-centered show, but it never made it past the scripting stages, leading the team to create an Avengers series instead.

Marvel announced in October 2008 that Marvel Animation and outside studio Film Roman would produce the Avengers series, with fifty-two episodes confirmed as being in production for a planned 2010 broadcast.

Due to executive changes during the second season, a planned multi-season story arc involving the Red Skull had to be compressed into the second half of season two, and other ideas were pushed to a cancelled third season.

An early script for the episode 'Powerless' featured a very different storyline, including Loki imprisoned with facial injuries within Yggdrasil, Amora the Enchantress freed from Surtur's control, Odin losing his eye and being replaced by Kurse, and Ms. Marvel rather than Iron Man being targeted to lose her powers.

Christopher Yost stated that the series originally planned to adapt the 'Emperor Doom' comic arc, featuring Wonder Man and the Scarlet Witch, which was eventually reworked into the episode 'Emperor Stark'; he even sold a copy of the original script for that episode.

The intended season 2 finale was originally meant to be a three-part story set on the Kree capital planet Hala, culminating in a final battle against Galactus there instead of on Earth, with the New Avengers' formation tied to Operation Galactic Storm rather than to Kang.

Characters such as Nova, Silver Surfer, Sentry, Hercules, Morgan le Fay, Taskmaster, Scarlet Witch, Quicksilver, and Doctor Strange were considered for the series but ultimately cut.

The Spider-Man appearing in the series was originally intended to be the same version as in The Spectacular Spider-Man, with Josh Keaton reprising the role, but he was replaced by Drake Bell, who voiced the character in Ultimate Spider-Man.

When the series was succeeded by Avengers Assemble in 2013, only Fred Tatasciore and James Mathis reprised their roles as the Hulk and Black Panther, respectively, while Drake Bell returned solely for Spider-Man guest appearances.

Following the series' 10th anniversary, story editor Christopher Yost posted (later deleted) tweets outlining hypothetical future seasons, including adaptations of Strange Tales, the West Coast Avengers, the X-Men, The Evolutionary War, House of M, The Infinity Gauntlet, Acts of Vengeance, and Secret Wars.

The first season holds a 100% approval rating on Rotten Tomatoes based on five reviews, with an average score of 7.50 out of 10.

The series was nominated for Best Sound Editing: Television Animation at the 2011 Golden Reel Awards.