Thomas confirmed his cameo during a speak with The Marvelists podcast hosts Peter Melnick and Eddie Wilson.
"I think it's okay to mention it, they just didn't want any secrets about the thing — nobody's gonna see me in that," Thomas said. "If you've got a magnifying glass, you can probably spot me."
Daredevil co-creator Stan Lee made a cameo in the Netflix series' first season, appearing in a blink-and-you'll-miss-it framed photo on the wall of a New York police station.
Thomas, best known for lengthy runs on The Avengers and X-Men, succeeded Lee as the editor-in-chief of Marvel Comics between 1972—1974. Thomas scripted 20 issues of Daredevil, his tenure on the title lasting between issues #51—#71.
Thomas' time on the book pit the horn-headed superhero against Samuel Saxon (the fright-inducing Mister Fear), mad scientist Paxton Page (Death's Head), washed up stunt motorcyclist George Smith (Stunt-Master), and racketeer leader Mason Hollis (Crime-Wave).
During Thomas' reign, Daredevil teamed with Spider-Man and Black Panther, and squared off against Cobra, Mister Hyde, Jester, recurring villains Wilbur Day (Stilt-Man) and Melvin Potter (Gladiator), as well as short-lived villains Brother Brimstone, Buck Ralston (Tribune), and the mercenary known only as Torpedo.
The writer co-created Turk Barrett, who has frequently popped up throughout Netflix's corner of the shared Marvel Cinematic Universe, appearing in Daredevil, Luke Cage, The Defenders, The Punisher and Jessica Jones.
The third season of the hit Marvel-Netflix series will see the return of Matt Murdock's arch foe Wilson Fisk, the Kingpin (Vincent D'Onofrio), who wrapped on the season just one week ago.
Season 3 is expected to partially adapt the famed 'Born Again' storyline by team Frank Miller and David Mazzucchelli, a story that saw the Kingpin systematically destroy the life of his hated horned enemy.
"There may be elements from Born Again, but I'm sure there will be elements that are unfamiliar and surprising and different in order for the show to be compelling to fans who know the comics very well," series lead Charlie Cox told The Hollywood Reporter last August.
"If we start making Born Again page-for-page, then the people who have read it and loved it — the hardcore fans — they won't have too much drama."
Daredevil is expected to debut its third season on Netflix later this year.