He is a cast member on Critical Role, a web series in which he plays Dungeons & Dragons with other voice actors.

Mom and 2010: The Year We Make Contact, and had membership of the Screen Actor's Guild at the age of seven months.

In 1985, Jaffe was a regular on the short-lived ABC sitcom Hail to the Chief as Willy Mansfield, son of the fictional first female president of the United States, who was played by Patty Duke.

[15][16] In November 2019, Amazon Prime Video acquired the streaming rights to the animated series The Legend of Vox Machina; Jaffe reprised his role as Percy.

[17][18] In May 2023, Darrington Press imprint announced the upcoming Candela Obscura campaign setting co-created by Jaffe and Chris Lockey for the Illuminated Worlds tabletop role-playing game system.