The writer tweeted an image of a plaque presented to him by Marvel Comics, which dates the end of his work on the franchise as Friday, September 21.
"The lovely Tom Brevoort just presented me with this. I'm quite touched," he wrote.
His run on the Avengers titles - which included the core book, New Avengers, Mighty Avengers, Dark Avengers and Avengers Assemble - began on February 7, 2004, and lasted over eight years.
Bendis will depart the franchise as part of the creative shake-up of Marvel NOW!
He will be writing All-New X-Men and a rumoured Guardians of the Galaxy title under the new initiative.
The conclusion of his run was first announced in late 2011.