Moraes got his start in martial arts with Muay Thai at age seven and began training in Brazilian Jiu-Jitsu at age 15. He saw national success in Muay Thai in his native Brazil, earning a pair of Muay Thai National Championships before switching full-time to MMA.
On December 2, 2011, Moraes fought Chris Manuel at XFC 15, winning via unanimous decision. On April 13, 2012, Moraes fought Jarrod Card at XFC 17, He won via knock out in 47 seconds of round one.
World Series of Fighting
In September 2012, Moraes signed with the World Series of Fighting. On November 3, 2012, Moraes made his promotional debut against former WEC Bantamweight Champion Miguel Torres at. Moraes defeated Torres via split decision. Following Moraes's victory over Torres it was announced that at Moraes would face Tyson Nam. On March 23, 2013, Moraes defeated Nam via knock out due to a head kick and punches in the first round. Moraes faced Brandon Hempleman at on August 10, 2013. Moraes won via unanimous decision. Moraes fought Carson Beebe at on October 26, 2013. He won via knockout due to punches in just thirty two seconds of round one. Moraes fought for the inaugural WSOF Bantamweight Championship against Josh Rettinghouse at WSOF 9. He won via unanimous decision to become the first ever WSOF Bantamweight Champion. Moraes was scheduled to defend his title against Josh Hill on September 13, 2014, at World Series of Fighting 13. However, Hill was injured and replaced by Cody Bollinger, with the bout being changed to a non-title, catchweight affair. Moraes won the fight via rear naked choke submission in the second round. Moraes was once again scheduled to defend his WSOF Bantamweight Championship against Josh Hill. The rescheduled fight took place on February 12, 2015, at in Edmonton, Alberta. Moraes won via unanimous decision to retain his WSOF Bantamweight Championship. Moraes faced Sheymon Moraes on August 1, 2015, at. Marlon Moraes won via rear naked choke submission in the third round to retain his WSOF Bantamweight Championship. On February 20, 2016, Moraes faced Joseph Barajas at. Moraes won via technical knockout due to leg kicks in the first round to retain his WSOF Bantamweight Championship. On May 10, 2016, it was announced that Moraes will rematch against Josh Hill for the WSOF Bantamweight Championship at on July 30, 2016, in the main event. Moraes won the fight via knockout in the second round. Moraes defended his title against Josenaldo Silva at on December 31, 2016. He won the fight via technical knockout due to Silva receiving a knee injury. On January 3, 2017, Moraes vacated the WSOF Bantamweight Championship after becoming an unrestricted free agent.
Ultimate Fighting Championship
In April 2017, it was announced that Moraes had signed with the UFC. He made his promotional debut against Raphael Assunção at UFC 212 on June 3, 2017. He lost the back-and-forth fight via split decision. Moraes faced John Dodson on November 11, 2017, at UFC Fight Night 120. He won the back-and-forth fight by split decision. Moraes made a quick return to the Octagon as he stepped in to replace Rani Yahya against Aljamain Sterling at on December 9, 2017. He won the fight via knockout in the first round. The win also earned Moraes his first Performance of the Night bonus award. After UFC Fight Night 123 in Fresno, the California State Athletic Commission flagged Moraes for gaining more than 10% of his weight back after weigh-ins. His jump from 135.4 pounds on weigh-in day to 155 pounds on fight day was a difference of 14.5%, well over commission regulations of staying within 10% of the contracted weight. CSAC will not license him for bantamweight bouts “without extensive medical documentation from a licensed physician certifying the weight class is appropriate and verified by CSAC physicians.” Moraes faced Jimmie Rivera on June 1, 2018, at UFC Fight Night 131. Moraes won the fight via first-round knockout due to a head kick and punches in just 33 seconds, becoming the first fighter to finish Rivera in MMA, and snapping Rivera's 20-fight win streak. This win earned him a $50,000 Performance of the Night bonus. Moraes faced Raphael Assunção in a rematch on February 2, 2019 in the main event at UFC Fight Night 144. Their first fight ended in a split decision loss for Moraes at UFC 212 on June 3, 2017. Moraes won the rematch in the first round by first dropping Assunção with two punches and then securing a guillotine choke submission. This win earned him the Performance of the Night award. Moraes faced Henry Cejudo on June 8, 2019 at UFC 238 for the vacant UFC Bantamweight Championship. He lost the fight via technical knockout in round three. Moraes faced former UFC Featherweight ChampionJosé Aldo at UFC 245 on December 14, 2019. He won the fight via split decision.
Championships and accomplishments
Ultimate Fighting Championship
* Performance of the Night vs. Aljamain Sterling, Jimmie Rivera, and Raphael Assunção