Born in Philadelphia, Pennsylvania, Marzano graduated from Central High School, and briefly attended Holy Family College, studying radiologic technology. He also attended Temple University, where he played for the Owls from 1982 to 1984. Marzano played as a catcher for the Temple Owls baseball team before getting drafted in the 1st round, 14th overall, in the 1984 entry draft by the Boston Red Sox of the American League.
He was a member of the silver medal-winning US Baseball Team at the 1984 Olympic Games. He founded the Marzano Baseball Academy in 1991.
Marzano became a cult hero in Seattle when he threw a haymaker at New York Yankees outfielder Paul O'Neill during a game in 1996. He is well known in Seattle for this incident which occurred after O'Neill complained to the umpire about a pitch that was high and inside.
At the time of his death, Marzano was in his second year of work with Major League Baseball's BaseballChannel.tv. He co-hosted the show Leading Off with Vinny Micucci every weekday morning.
Marzano died unexpectedly at age 45 at his home on Passyunk Avenue in the city's South Philadelphia neighborhood. He was found after having fallen down a flight of stairs. It was originally speculated that he may have suffered a heart attack, but the Medical Examiner's Office reported on July 17, 2008 that his death was actually caused by positional asphyxia after the way his body landed after the fall. His last public appearance was on Daily News Live on Thursday, April 17, from the Wachovia Center. He is survived by his wife, two daughters, and two grandchildren.