The 31-year-old plays a villain named "Heather Rockrear" in the movie. TV Guide reported in July that her character is the sidekick of Zachary Levi's evil Thin White Duke character.
"She's a sexy badass," Flair said of her role, that lets her show off her wrestling moves in the movie.
Flair's very presence in the movie is a reference to Psych's long list of wrestling guest stars. John Cena, Stacy Keibler, Michie James, The Miz, The Bella Twins and Big Show all made cameos during the show's original run.
"This was about saying thank you," James Roday told Entertainment Weekly on Nov. 30. "This was basically our love letter back to our fans, who let us crowd-surf for eight years."
Roday, Hill, Timothy Omundson, Maggie Lawson, Kirsten Nelson and Corbin Bernsen all returned for Psych The Movie. Jazmyn Simon, Hill's real-life fiancée, will play Gus' new love interest. The movie was written by Roday with Psych creator Steve Franks.
The original Psych ran from 2006 to 2014. The show only earned an Emmy nomination for music in 2010, but it gained a cult following and fans have been rewarded with the movie.
Psych: The Movie debuts on Thursday, Dec. 7 at 8 p.m. ET/7 p.m. CT on USA.