Sandro made his professional MMA debut in November 2004. He fought primarily in his native Brazil, amassing an undefeated streak of 12–0 before debuting for the WorldVictory Road Presents: Sengoku promotion.
Sandro participated in World Victory Road's Sengoku Featherweight Championship Tournament, losing by a "must decide" decision in the semi-finals to judo specialist and former UFC veteran Michihiro Omigawa. Scores were 30–30, 30–30, 30–29 Sandro but the judges with draws selected Omigawa in a "must decide" decision, giving him the "must decide split decision" 2–1. His challenged Sengoku Featherweight Champion, Masanori Kanehara at World Victory Road Presents: Sengoku 13. Sandro won via KO 38 seconds into the first round. Kanehara was sent out of the ring in a stretcher. After the fight Sandro was ranked the No. 5 Featherweight in the world by Sherdog. On a side note, Marlon weighted 166 lbs one week before the fight. Sandro lost the Sengoku Featherweight Championship to Hatsu Hioki at World Victory Road Presents: Soul of Fight on December 30, 2010 by unanimous decision. Hioki dominated nearly every round of the fight, and Sandro was given a yellow card in the first round. Sandro was nearly submitted several times in the final round by a chicken wingarmlock, then by an armbar.
On February 23, it was announced Sandro had signed a multi-fight deal with Bellator Fighting Championships, and will be competing in their Season Four Tournament fights. Sandro made his debut with the promotion at Bellator 46 against Genair da Silva in his quarterfinal match of the . While a seemingly clear-cut decision win, Sandro won the fight on only two scorecards. A third judge scored the bout 29–28 for da Silva, which resulted in a split decision victory for Sandro. Sandro faced Nazareno Malegarie in the semifinals at Bellator 47. He dominated Malegarie, and won the fight via unanimous decision. Sandro fought Pat Curran at Bellator 48 in the finals of the tournament. After controlling the fight with his superior striking, Sandro lost via head kick KO late in the second round. Sandro rebounded from the first KO loss of his career by submitting fellow Brazilian Rafael Dias in the first round at Bellator 58. In March 2012, Sandro entered the Bellator Season Six Featherweight Tournament, where he defeated Roberto Vargas by submission in the first round. In the semifinals at, Sandro defeated Alexandre Bezerra via split decision. Sandro faced Daniel Mason-Straus in the tournament finals at. He lost the fight via unanimous decision. Sandro faced contestant Dustin Neace on November 16, 2012 at Bellator 81. Sandro won the fight via technical submission due to a rear-naked choke in the first round. Sandro then participated in the at Bellator 88 on February 7, 2013, he faced Akop Stepanyan in the quarterfinal round. Sandro won the fight via majority decision. In the semifinal, Sandro faced Magomedrasul Khasbulaev at Bellator 92 and lost via third-round TKO.
Return To Pancrase
After a five-year absence, the former King of Pancrase Featherweight Champion returns at Pancrase 252: 20th Anniversary. Sandro took on Yojiro Uchimura. The fight went to a draw. Next Sandro fought the current King of Pancrase Lightweight Champion in a Featherweight bout in the main event of Pancrase 266, but came up short losing by split decision.
