Stephen was born in St. Louis, Missouri to Marlene Lombardo and Stephen Martines. He is also nephew to Guy Lombardo. Martines has two siblings, a sister Melissa (age 30) and a half-sister Amanda (age 19). Coming from a divorced home, he lived with his mother until the age of 15 and then went to live with his father, with whom he was very close. Stephen was a select soccer player at an early age, having been scouted at the age of 14 by many colleges and professional teams, both nationwide and international. He attended CBC High School (Christian Brothers College) in Clayton, Missouri, graduating in 1993.

After turning down many scholarship offers to play soccer at some of the top schools in the country, Stephen chose to attend then-named SMS (Southwest Missouri State University) which is now known as Missouri State University. In October 1994 his father passed suddenly due to a massive heart attack. He left school, quit playing soccer and went back home. After burying his father, with the intent of finishing school, he enrolled at Webster University, in Webster Groves, Missouri, after a scout called him and asked him to come play soccer there. That year, the school won the National Championship, a first in the school's history.

In 1998, he was discharged from the United States Air Force after incurring a career-ending injury to his right knee during a game. After a year of rehabilitation, he found himself on the road to Hollywood to begin his career. In the early 2000s, Martines also recorded a few songs produced by Pink Drummer Mark Schulman.