Carla Esparza is from California's Redondo Beach. While attending Redondo Union High School, she competed in basketball, running, and wrestling. Esparza won wrestling tournaments, which earned her a four-year wrestling scholarship to attend Menlo College. In 2005, she trained in boxing at Broadway Gym in Los Angeles. A year later she practiced Brazilian Jiu-Jitsu (BJJ) at the Gracie Academy in Torrance founded by Rorion Gracie. She joined Team Oyama, formed by Colin Oyama, where she trained in Mixed Martial Arts (MMA), BJJ, and Muay Thai. Esparza had her professional MMA debut in 2010 against Cassie Trost, winning by third round technical knockout. She next had decisive submission wins over Karina Hallinan and Lacey Schuckman. With three days notice, Esparza replaced 'Angela Magana' to fight Megumi Fujii in a quarter-final tournament match at Bellator Fighting Championships: Bellator Fighting Championships 24 (2010). The tournament was to crown Bellator's strawweight (115 pounds) champion. Esparza experienced her first loss when Fujii submitted her by arm-bar in round two. Esparza next fought Nina Ansaroff in Crowbar MMA and won a split decision. She submitted Yadira Anzaldua via choke in Evolution Combat Sports Championship. She returned to Bellator to fight Jessica Aguilar at Bellator Fighting Championships: Bellator Fighting Championships 46 (2011), and lost by split decision. Esparza competed in Xtreme Fighting Championships where she matched up with Felice Herrig. They fought during XFC 15: Tribute (2011), and Esparza used wrestling to win by unanimous decision. Esparza and Angela Magana agreed to fight each for the strawweight title at MEZ Sports in March 2012. The bout never happened because Magana was injured in a car accident.

Esparza signed with Invicta Fighting Championships (Invicta FC) in 2012, and fought Sarah Schneider at Invicta FC 2. Schneider took her to the ground twice, and attacked from top. Esparza escaped and threw Schneider to the ground. Schneider attacked Esparza's left foot with a heel hook while Esparza punched her. Back in stand-up, Schneider takedown was thwarted by Esparza who put her on her back and attacked. Esparza started round two with punches which connected on Schneider who tried for an unsuccessful takedown. Esparza controlled her opponent's head and briefly went for a rear-naked choke from full mount. She attacked Schneider with punches on the ground, then another brief attempt at a rear-naked choke. Esparza maintained her striking advantage over Schneider, took her down again, and landed more punches. Schneider interrupted Esparza's momentum with an inverted triangle choke. The hold was broken, and Esparza resumed her punches until the bout was stopped in round two. Esparza competed at Invicta FC 3 with Lynn Alvarez. Alvarez connected with early left jabs. Esparza got a single-leg takedown and controlled Alvarez from the side and pressed her knee to her opponent's stomach while landing punches, which won her the fight in round one by technical knockout.

Esparza met Bec Rawlings at Invicta FC 4 for the vacant strawweight title. Hyatt replaced Claudia Gadelha due to a broken nose. Esparza reacted to Hyatt's punches by taking her to the ground and controlled her for most of the first round, nearly getting a rear-naked choke. Esparza earned a swift takedown in early round two, and a second one after Hyatt got up. Esparza was endangered after Rawlings went for an arm-bar. She escaped and received Hyatt's knees to her face, and earned a third takedown in the round. A slow exchange of strikes happened in the third round. Esparza got another takedown of Hyatt where the two battled and was later stood up by the referee. Esparza was placed on the defensive by Hyatt's punches. She head-locked Hyatt and tossed her to the ground. Round four started with Hyatt pursuing Esparza with punches which landed. Esparza shoot forward and eventually got her opponent on the ground where she again controlled the action. Esparza attempted another rear-naked choke then an arm-bar submission which Hyatt eluded and ended up on top. Hyatt attacked from the top then on the feet when Esparza stood up. Esparza ended the round by securing another head-lock toss to the ground. The fifth and last round saw a still aggressive Hyatt land punches. Esparza endured the attack and took her down by single-leg. The bout was stood up and Hyatt benefited with landed strikes on Esparza, who waited and took her down ground again. Hyatt quickly stood up and got the better of the striking exchange, forcing Esparza against the fence, knocked her down and attacked her on the ground until the round expired. By unanimous decision, Esparza won the Invicta FC strawweight championship. That year, she and Angela Magana used the media to express their disagreements. Esparza disputed the claim of being in a car accident, and felt that Magana was avoiding a drug test. Esparza stated that Magana also avoided fighting Megumi Fujii, Rosi Sexton, Tara LaRosa, and Stephanie Eggink. Magana countered there was an accident, that she suffered nerve damage, and got a hospital bill worth $30,000. She also said that in 2007, she broke her back in a three-story fall and committed to a fight while recovering. Esparza's first Invicta FC strawweight title defense was scheduled at Invicta FC 6: Cyborg vs. Coenen II (2013) with Ayaka Hamasaki. A knee injury forced Esparza from the bout, and she was later booked to defend against Claudia Gadelha at Invicta FC 7: Honchak vs. Smith (2013). Gadelha withdrew due to stomach illness a day before the bout.

Carla Esparza never defended Invicta FC's strawweight title. Fours days after Invicta FC 7, an agreement was announced where Zuffa's UFC acquired the Invicta FC contracts of Esparza and ten other strawweights. They would compete on the The Ultimate Fighter (2005) to inaugurate UFC's strawweight champion. Ranked the number one strawweight, Esparza was chosen by Anthony Pettis to join his Team Pettis against Team Melendez lead by Gilbert Melendez. Esparza allied with former opponent and Team Pettis teammate,Felice Herrig. On the show, there were no indications of any of her prior issues with another Team Pettis teammate, Angela Magana. Esparza won three exhibition bouts by beating Angela Hill by rear-naked choke, won a majority decision over Tecia Torres, and a unanimous decision against Jessica Penne. Esparza advanced to the finals with Rose Namajunas at The Ultimate Fighter 20 Finale. Namajunas was the aggressor and they exchanged strikes. Esparza got a takedown and landed punches. Namajunas fought her way back up, Esparza briefly got a second takedown, and later got a third takedown with longer ground control. Esparza got a fourth takedown near the end of the first round. Namajunas continued being the aggressor in round two, and avoided being taken down. Esparza ran in and got a double-leg takedown, then attacked with elbows, punches, and later allowed her opponent to stand. Namajunas tried for a takedown and Esparza reversed her to end up on top. Esparza unleashed a punching attack until round's end. Esparza took Namajunas down early in round three by holding her right ankle. Esparza resumed a punching attack, then applied a rear-naked choke to submit Namajunas and became UFC's first strawweight champion.