At the age of fifteen, Hoppus got his first bass from his father after helping him paint his house. Mark played bass and sang in the band Pier 69, primarily covering songs by The Cure. He also played in a band called The Attic Children in 1988. He later moved to San Diego to continue his studies in college, where he met Tom Delonge (another blink-182 member) through his little sister, Anne Hoppus. Delonge was a friend of Anne's boyfriend, Kerry Key, and constantly complained about wanting to join a band. She finally introduced Hoppus and Delonge in August 1992.
Hoppus and DeLonge, with their friend, drummer Scott Raynor, decided to form a band in 1992. They were under the name "Duck Tape" until their third show when Delonge said he liked another name…" companysblink", but an Irish techno band was already using that name and threatened them with a court case, so they changed their name to blink-182.
Hoppus appeared on MxPx's eighth studio album Panic on "Wrecking Hotel Rooms," providing backing vocals. He is also on the track and in the video "I'd do anything" by Simple Plan from their debut CD "No Pads, No Helmet… Just Balls".
Mark also co-owns several popular punk company, Loserkids, Macbeth, and Atticus. The name Atticus is taken from a character from the book 'To Kill a Mocking Bird.' Mark feels he has not had any influence in how the companies are being run in the past year and are in the process of selling his shares, Mark is a record producer. Producing the second album of Minnesota band Motion City Soundtrack, Commit This to Memory and has also been producing the two piece Idiot Pilot.