The 46-year-old actor explained on Thursday he planned to direct and star in the next Batman movie, but couldn't "crack" the story and thought it best to leave the project to someone else. Kimmel asked him if there was a statement he wanted to make and Affleck replied, "I don't know. I guess. . . I am not Batman."
Kimmel officially retired the cape and cowl from Affleck's costume. To make room for the item, Kimmel said he would get rid of another piece of memorabilia in his collection -- the sparkly thong Affleck's longtime friend Matt Damon wore in the TV movie Behind the Candelabra.
"Please give it to him or have it destroyed," Kimmel said.
"Thank you. I will," Affleck said.
The cape was then revealed to say "Batfleck 12" on the back.
"That's (Tom) Brady's number. You can't be a hero unless you're wearing No. 12," Affleck said, referring to the New England Patriots legend.
The studio said Affleck -- who played the caped crusader in 2016's Batman v Superman: Dawn of Justice, briefly in 2016's Suicide Squad and in 2017's Justice League -- would not be reprising his role in the new movie.
"Excited for #TheBatman in Summer 2021 and to see @MattReevesLA vision come to life," Affleck tweeted at the time.
He did not publicly, explicitly address his departure until his appearance on Kimmel.
No replacement has been announced yet.