Marrero began wrestling for Daniel Boone High School in Berks County, Pennsylvania and placed sixth in the state tournament as a Heavyweight.
Marrero was sidelined by a near-fatal car accident which took him six months to recover, but later came back to win over 40 matches and qualify for the Junior College National Tournament.
[2] Marrero's first five professional bouts were against local opponents in small fight promotions along the New Jersey shore.
Marrero made his UFC debut against a much larger and more experienced opponent in Cheick Kongo who already had two wins for the organization.
Marrero competed for American Top Team's camp in the International Fight League and made his debut for the organization on April 4, 2008 at IFL: New Jersey where he faced Mike Ciesnolevicz.