Mil Máscaras appeared in World Wrestling Federation (WWF, now called WWE) in the 1970's. He performed at Madison Square Garden several times, making him the first masked wrestler in the Garden, where he defeated The Spoiler (who was not permitted to wear his mask). During this time, he feuded with Superstar Billy Graham over the WWF World Heavyweight Championship.
Máscaras also wrestled in World Championship Wrestling (WCW) in 1990, where his most notable match was a match with Cactus Jack at Clash of the Champions X: Texas Shootout on February 6, 1990 in the Memorial Coliseum in Corpus Christi, Texas.
Máscaras' first American pay-per-view appearance was competing in WWF's 1997 Royal Rumble match. He eliminated himself, diving off the top rope out of the ring onto Pierroth Jr., whom he himself had just eliminated.
In April 2012, Máscaras was inducted into the WWE Hall of Fame by his nephew Alberto Del Rio.