The former "Dallas" star is one of three well-known names signing on for the FX series' fourth season, which will roll out later this year. Along with Hagman, Kathleen Turner will have a recurring role, and Brooke Shields will appear a guest star, according to The Hollywood Reporter.
Sanaa Lathan ("Something New") had previously been cast in a multi-episode arc on the show.
Hagman, who earned two Emmy nominations for playing the diabolical J.R. Ewing on "Dallas," is set to play the wealthy husband of Lathan's character. The couple buys the cosmetic surgery practice run by Drs. Sean McNamara (Dylan Walsh) and Christian Troy (Julian McMahon).
The part will be Hagman's first TV role in several years. He last went before the cameras in a 1998 "Dallas" movie subtitled "War of the Ewings."
Turner ("Body Heat," "The War of the Roses"), meanwhile, will play a phone-sex operator who fears her stock-in-trade -- her voice -- is failing her. She comes to McNamara/Troy for vocal-cord surgery. Her recent credits include a guest spot on "Law & Order" last season and voice work on the forthcoming animated movie "Monster House."
Finally, Shields will guest star in "Nip/Tuck's" season premiere as a psychologist treating Christian. Her most recent TV credit -- not including the battle of words she had with Tom Cruise last year over her use of antidepressants -- was a recurring part on "That '70s Show."