Mariano was born in Hyde Park, Boston, Massachusetts, and raised in Canton, Massachusetts. He is of Italian descent. He graduated from Xaverian Brothers High School in 1994, where he played golf and hockey. In 1999, Mariano graduated with a Bachelor of Arts degree in psychology from Boston University. He made the BU hockey team in 1995 as a freshman, however he declined to play for coach Jack Parker after he was told that he would not receive much ice time. At the time he first played "Survivor" in 2001, he was 25 years old and continuing to coach the hockey team.