Slick debuted in the WWF alongside Butch Reed in August 1986. Soon after, he purchased a "half interest" in "Classy" Freddie Blassie's heel stable. The aging Blassie was experiencing declining health, and was being slowly phased out of storylines. Slick eventually took over all managerial duties from Blassie, initially managing Nikolai Volkoff and The Iron Sheik. During this time, Slick also sold the contract of Hercules (another wrestler of Blassie's former stable) to fellow heel manager Bobby "The Brain" Heenan for a "pile of money".
Slick's biggest success as a manager came when he took Akeem (previously known as the One Man Gang) and the Big Boss Man, the Twin Towers, to main event matches against Hulk Hogan and WWF Champion "Macho Man" Randy Savage, The Mega Powers. Slick would also manage The Bolsheviks (Volkoff and Boris Zhukov), Rick Martel, Power and Glory (Hercules and Paul Roma), and The Warlord.
In November 1991, Slick went on an extended leave of absence after being powerslammed by Davey Boy Smith. He returned a month later as the face "Reverend Slick", denouncing his shady past and striving to become a better man. He sometimes appeared on WWF programming to give a "sermon" that was usually a simple, uplifting message. Then later in November 1991, he joined the crew on Prime Time Wrestling as a regular full-time panelist, providing commentary and insight on storylines and matches until the show ended in 1993, as well as the co-host of WWF Wrestling Spotlight with Gene Okerlund. After Prime Time ended, his main storyline under this gimmick was to take Kamala from the hands of Harvey Wippleman and Kim Chee to convince him that he was not just a Ugandan monster who deserved constant berating, but a man, and he tried to instill Kamala with self-respect (including a memorable segment where Slick and Kamala went bowling).
On April 1, 2007, Slick appeared at WrestleMania 23, dancing with various WWE wrestlers and legends.
Slick made an appearance on the "Old School" edition of WWE Raw on November 15, 2010, joining legends the Iron Sheik and Nikolai Volkoff in the ring.
On July 23, 2012, Slick made a special appearance on Raw 1000. He served as the reverend presiding over the wedding that involved Daniel Bryan and AJ Lee.
On April 2, 2016, Slick appeared to induct Big Boss Man into that year's class of the WWE Hall of Fame.