A native of Highland Park, Illinois, David Marconi was passionate about filmmaking from an early age. After winning several high-school film making competitions, Marconi was awarded an alumni merit scholarship to attend the University of Southern California's film school. After graduation, he landed his first job as Francis Ford Coppola's assistant on "The Outsiders". Following that, Coppola promoted Marconi to production supervisor/2nd unit on "Rumble Fish".

In 1993, Marconi wrote and directed his first feature film, "The Harvest", a visually detailed stylish noir starring Miguel Ferrer and Leilani Sarelle. Shortly thereafter, Simpson/Bruckheimer commissioned Marconi to write an original screenplay, A high-tech thriller dealing with privacy issues titled "Enemy of the State", starring Will Smith and Gene Hackman, the film would gross over 250 million dollars worldwide. On the success of Enemy of the State, Marconi would redevelop Jerry Bruckheimer's television series "Soldier of Fortune".

Marconi also has co-authored three serialized novels with Flint Dille: "Agent 13, The Midnight Avenger", "Agent 13 and the Serpentine Assassins" and "Agent 13 and the Acolytes of Darkness", An action-adventure series set in the 1930's.