In 1965, the Sheik made his debut for the World Wide Wrestling Federation. On September 25, 1967, he had a 20 minute draw with Édouard Carpentier.
In 1968, he was brought into the WWWF for title matches with then-champion Bruno Sammartino. They met three times in Madison Square Garden—Sheik won the first via count out on October 28, he was disqualified in the second November 18, and he lost to Bruno in a Texas Death Match via submission when Bruno grabbed a foreign object and hammered Sheik's arm to a bloody pulp on December 9. Sammartino and Sheik also had a series of matches in Boston in January and February 1969. They fought in three steel cage matches one in Philadelphia and two in Boston.
On November 18, 1972 he lost to WWWF Champion Pedro Morales by count out at Boston Garden.
In 1994, he had a brief run in Extreme Championship Wrestling where he teamed with Pat Tanaka against Kevin Sullivan and Taz.
When his nephew Sabu joined WCW in 1995, the Sheik joined him as his manager. During a match with Mr. JL, Sheik's leg was broken by the wrestlers during a spot.
On January 18, 2003, he passed away.
On March 31, 2007, The Sheik was inducted into the WWE Hall of Fame by his nephew, Sabu, and Rob Van Dam.