In September 2000, Blum voiced the role of TOM, the robotic host of Toonami shown on Cartoon Network (replacing Sonny Strait), as the second through 4th incarnations of the character right up to the block's cancellation on September 20, 2008 delivering the final lines uttered on the block, echoing his early role of Cowboy Bebop's Spike Spiegel, to recent revival of the block on May 26, 2012. He is also the voice of Amon in The Legend of Korra and 7-Eleven's "Oh Thank Heaven" television and radio advertisements and for his work with Vic Mignogna in a scratch-made sound bite series parodying Anheuser-Busch's "Real Men of Genius" radio ad campaign, titled "Real Fans of Genius". Revealed by Blind Ferret Entertainment on November 15, 2012, it was announced that Blum will be playing Harry, "the Homeless Bum," in Least I Could Do: The Animated Series.
He is also well known in American-based animation; as the voices of Heatblast, Ghostfreak, and Vilgax in the Ben 10 franchise, Jamie in Megas XLR, Yakky Doodle and Clamhead in Harvey Birdman, Attorney at Law, Smytus in My Life as a Teenage Robot, and his voice portrayals of Starscream in Transformers: Prime and Count Vertigo in DC Showcase: Green Arrow as well as in Young Justice, The Red Skull, Beta Ray Bill and Wolverine in The Avengers: Earth's Mightiest Heroes and as Melbourne O'Riley in What's New, Scooby Doo?.
See his massive voice acting credits list here.