Denny Carmassi was born into a family of drummers; his father, his uncle, and his brother each played the drums. Some of Denny Carmassi's earliest memories are his father rehearsing after work with his band in the kitchen of their home. Occasionally they allowed young Denny Carmassi to sit in with them.
Denny Carmassi's father exposed Denny to great musicians, including Buddy Rich, Jimmy Vincent, Louie Prima, Ray Charles, Earl Palmer, D.J. Fontana, Al Jackson Jr., and many more.
Out of high school, Denny Carmassi joined a band called Sweet Linda Devine. The band recorded an album in New York, but before long they parted ways. Denny Carmassi went on to work with several local bands in the Bay Area and began working with Montrose and Sammy Hagar in the 1970s.
Throughout the 1980s and 1990s, Denny Carmassi worked with the Gamma, Heart, Cinderella, .38 Special and Stevie Nicks, Ted Nugent, and Whitesnake. He also performed on several film soundtracks.
Denny Carmassi continued to work with these artists in the 21st century; he also recorded with Kim Carnes, Randy Newman, Al Stewart, and 707.