Baldwin has worked in theater extensively, appearing as Mushnik in Little Shop Of Horrors, Dr. Zubritsky in Neil Simon's Fools, Count Otto Von Bruno in Bullshot Crummond, and several other productions. Primarily known as a voice actor, some of his roles include Boris The Cosmonaut Monkey in Brandy & Mr. Whiskers, Daddy Bailey in Xiaolin Showdown, Jack M. Crazyfish in SpongeBob SquarePants, and various characters in the Cartoon Network series Star Wars: The Clone Wars. His voice can also be heard on numerous video games, such as Rainbow 6: Lockdown, F.E.A.R., Bioshock, and others.
Baldwin attended the University of Houston with fellow voice actor Jeff Bennett.
Greg Baldwin was raised in Spring, Texas, and currently resides in the San Fernando Valley. He has been married to Melissa Baldwin for twenty-six years and the couple have two children: Sydney and Cooper.
Being Mako Iwamatsu's understudy and a long-time student of his voice, Baldwin performed a few one-off lines Mako was unable to complete in Book Two and then went on to do all of Iroh's voice work in Book Three. Although his vocal timbre is lighter than Mako's, Baldwin replicates Mako's unique accent, pronunciation, syllable stressing, and gravelly undertones in his performance rather than using a different style for Iroh.
Being understudy and a long-time student of Mako's voice, Baldwin also voiced Aku (from the Cartoon Network series Samurai Jack) in the 2009 video game FusionFall.