Mallaber was also the drummer/percussionist and backing singer for the 1980s band Kid Lightning, who released an album with Gerard McMahon in 1981 entitled Blue Rue.
Mallaber also plays keyboards and sings on many albums by well-known rock artists. He is probably best known for his work as drummer/percussionist, backup singer, and co-composer for The Steve Miller Band. He has also played with the Greg Kihn Band.
Mallaber was also the main studio drummer for Eddie Money for most of his earlier recordings and has played on many Bruce Springsteen and Van Morrison solo albums. Gary was also in the 1974 Brian DePalma film Phantom of the Paradise, in addition to performing on the film's soundtrack he is also seen in the film as the drummer for the Juicy Fruits, the Beach Bums, and The Undeads.