U Los Angelesu, pojavila se u njenoj predstavi, ''Sweetheart,'' 1999.; u ''The Berlin Circle,'' za šta je osvojila [[LA Weekly Theater Award]] i [[Back Stage West Garland Award]] 2000. godine; i u predstavi ''Mayhem'' 2003.
Mullally starredje in2007-2008. theigrala newElizabeth u [[Mel Brooks]]ovom musicalmjuziklu, ''[[Young Frankenstein (musical)|Young Frankenstein]]'',. asLik Elizabeth. The role was madefamousje byproslavila [[Madeline Kahn]] inu thefilmu [[Young Frankenstein|originaloriginalni film]]. She is featured on the cast album and performs "[[Please Don't Touch Me]]," "Deep Love," and "Surprise." Her character is the wealthy fiancée of the title character, Dr. "Fronkensteen", who breaks her engagement with Frankenstein after falling in love with his monster. Her co-stars included [[Tony Award]]-winners [[Roger Bart]], [[Sutton Foster]], [[Andrea Martin]], and [[Shuler Hensley]]. Rehearsals for the production began in June 2007 and a pre-Broadway run opened to mixed reviews in [[Seattle]], [[Washington]]. The show premiered after previews on November 8, 2007. Mullally performed her final performance at the [[Hilton Theatre]] on August 3, 2008 to focus on the new television series in which she will play the role of [[Alicia Silverstone]]'s mother.<ref>[http://www.broadwayworld.com/viewcolumn.cfm?colid=29200 Leavel, Ragusa and Sullivan Join 'Frankenstein' This Summer (BroadwayWorld.com)<!-- Bot generated title -->]</ref> Michele Ragusa took over the role of Elizabeth following Mullally's departure.
Mullally is also a singer and performs in her own group called The Supreme Music Program. The band has released three albums, ''The Sweetheart Break-In'', ''Big as a Berry'' and ''Free Again!''. She recorded a duet with [[Carly Simon]] on the track ''The Right Thing To Do'' for the ''Will & Grace: Let the Music Out!'' soundtrack. The third album from the SMP was originally titled ''The Many Moods… Vol, 1''. However, the title was changed before going to print. The third album, ''Free Again!'', was released online on July 28, 2007.
