The series follows struggling Hollywood writers and actors supporting themselves as caterers.
"My character, Lydia, comes in as a breath of fresh air," said Mullally in a recent interview from New York City. "She bursts onto the scene from the Midwest with her 13-year-old daughter Escapade, who is going to be the next Hannah Montana."
Mullally, 51, had her share of odd jobs before breakout Broadway roles in the mid-'90s, and then playing boozy Karen Walker on "Will & Grace" from 1998 to 2006.
"One time I got hired because I wore a size-6 shoe," the L.A. native recalled. "So I got hired to go do the shoe show, which was down at the Convention Center. And what it consisted of was me ... (Mullally hesitates) ... in a hotel room ... trying on shoes for ... a bunch of Japanese guys," she added, laughing.
The odd, if more lucrative, jobs continue for Mullally, who can be seen dancing around a supermarket in lavish TV and online commercials for a butter substitute.
"And how gorgeous did they make me look?" Mullally asked. "I felt like the best I've ever looked was on a butter commercial!" she added, laughing.
Karen Walker will live on in the stage show "Karen: The Musical," currently in development. Mullally said she also will be returning to another sitcom, "Parks and Recreation," where she made a guest appearance last year as the ex-wife of the character played by her real-life husband, writer and actor Nick Offerman.
"I'm really lucky, because Nick and I are homebodies, strangely enough. We're not Hollywood-y at all," she said. "Like I wonder, when I see a reality show that's set in Los Angeles with really tan women with giant boobs that do a lot of drugs. 'Where are they?' 'Cause I've lived there for 25 years and I've never seen them. We have a normal life and we just kind of keep it on the down low."