[3] In 1993, when he was about 11 years old, he provided the voice of Junior Healy in the USA Network animated series Problem Child.

In anime, notable roles he played include Arashi Fuuma and Sai in Naruto and Naruto: Shippuden respectively, Kai Miyagusuku and Katao in Blood+, Shoutmon and Cutemon in Digimon Fusion, Joseph Joestar in JoJo's Bizarre Adventure, Gurio Umino in the Viz Media dub of Sailor Moon, Kensuke Aida in Neon Genesis Evangelion, Char Aznable in Mobile Suit Gundam: The Origin, Death Gun in Sword Art Online, Ban in The Seven Deadly Sins, Satoru Fujinuma in Erased, Knuckle Bine in Hunter x Hunter, and Jack in Beastars.

and Stitch & Ai, taking over from the character's creator and original voice actor Chris Sanders.

In video games, he voiced Eric Sparrow in Tony Hawk's Underground and its direct sequel Tony Hawk's Underground 2, Young Xehanort from the Kingdom Hearts series, Jared Miller in Halo 4, Jusis Albarea in The Legend of Heroes: Trails of Cold Steel series, Mega Man in Mega Man 11, and had two major roles in Fire Emblem: Three Houses: Lorenz Hellman Gloucester and Caspar von Bergliez.

On May 4, 2019, Diskin won the "Outstanding Performer in a Preschool Animated Program" Daytime Emmy award for his role of Gonzo and Rizzo in Muppet Babies.