Eddy started amateur wrestling at the age of 11, and after eight years of hard training, he turned pro at 19. At first, he worked from EMLL(Expresa Mexicana de Lucha Libre), wrestling with a mask as 'Mascara Magica'. It was here where he learned the high-flying lucha libre skills and mat techniques. He won the WWA World Trios title with nephew Chavo and brother Mando in 1988. Four years later, he captured the WWA World Welterweight title.

In 1993, Eddy joined the newly formed AAA. Amazingly, on one AAA TV show, he became the first Mexican wrestler in history to take off his mask by his own will. Rather than participating in what could have been a very lucrative and well-earned Mask Vs Mask match, Eddy explained to the onlooking crowd that Mascara Magica was not someone he had ever wanted to be and that it was something that had been forced on him by his former promotion. He claimed it was time to just be himself. As the stunned crowd looked on, Mascara Magica removed his mask to unveil Eddy Guerrero.

He then revived his father's famous tag team, La Pareja Atomica, with El Hijo Del Santo. Del Santo was the son of Gory's tag partner in the 60's. When 'The Love Machine' Art Barr somehow convinced Eddy to turn on El Hijo, and they formed La Pareja del Terror, later and better known as Gringos Locos. They were considered the greatest heel duo in Mexican history as they soon grabbed the AAA Tag Team titles. On November 4, 1994, Gringos Locos lost a Hair Vs Hair match against Eddy's old partner El Hijo Del Santo, along with his new partner Octagon. This match was held in Los Angeles, CA and was the first ever American lucha libre PPV, named "When Worlds Collide". This was co- promoted by AAA and World Championship Wrestling (WCW). It was sadly their final match. On November 23, while napping with his young son, Art died in his sleep from unknown causes. Eddy was deeply saddened as Art was his best friend.

Shortly after Barr's death, Eddy left AAA for Extreme Championship Wrestling. He only had a brief stay there but he won the ECW TV Title on two occassions. He also had a memorable fued with 'The Iceman' Dean Malenko. Their two out of three fall and 30 minute time limit draw matches were very nearly clinics of holds, reversals, maneuvers and skill, and are considered some of their best encounters ever. In their final match in ECW, Malenko and Guerrero wrestled a best of three falls match, splitting the first two wins and simultaneously pinning each other for a draw in the third and left the ring accompanied by a standing ovation from the crowd. This is something rarely seen in wrestling but both men hard earned the respect of the fans, even if their styles differed from the Hardcore style of ECW.

However, after only 7 months in Philadelphia, Eddy was forced to leave due to a working agreement with NJPW(New Japan Pro Wrestling). He honed his skills even further there and wrestled against the likes of Wild Pesagus(Chris Benoit) and Jushin 'Thunder' Liger. He teamed up with The Great Sasuke to win the NJPW Junior Heavyweight Super Grade Tag titles. In Japan he worked first under his real name and then later as masked wrestler Black Tiger. In 1996 he won the NJPW Top of the Super Juniors tournament as Black Tiger.

Eddy first wrestled in WCW temporarily in 1995 and then left Japan and then signed a full-time contract. He first fueded with Rey Mysterio Jr and continued his famous war with Dean Malenko. Mysterio and Guerrero wrestled what is considered by many to be one of the Top 10 matches of all time at Halloween Havoc '98 in a Belt Vs Mask match. Eddy also hilariously bossed around his nephew Chavo and won the US Title and two Cruiserweight straps.

When the nWo took over WCW, Eddy created the Latino World Order to combat Eric Bischoff. He got several luchodores to join. However, Rey Jr was unwilling to join, so Eddy beat him in a "lose and join the LWO" match. Rey lost and joined. Eventually the LWO took the money from then-president Ric Flair. All of them took off their shirts, except for Rey Mysterio, suprisingly.

On New Year's eve 1998, Eddy fell asleep at the wheel, crashed, flew through the sunroof and landed on a pile of sand. An extremely odd series of concidences was what kept the crash from being fatal. However, his hip was broken.

When Eddy returned in mid-1999 he went through the entire former LWO members, starting with Juventud Guerrera and Psychosis. Eddy then joined The Filthy Animals with Kidman, Rey and Konnan.

He began a fued with Kidman over Torrie, Kidman's girlfriend, and he pinned Kidman with the Frogsplash on the 11.15 NITRO. Six weeks later, The Animals reformed. However, the Kidman match was Eddy's last in WCW.

When Kevin Sullivan took the reigns of WCW in January 2000, Eddy asked for his release and got it. The next day, he appeared on WWF Raw with Chris Benoit, Dean Malenko and Perry Saturn.