When Hollywood musicals stopped giving work, Marni began working in theater interprets Eliza Doolittle in My Fair Lady and Fraulein Schneider in Cabaret. In the late 1970s and early 80s, introduced Boomerang, a children’s program on KOMO-TV, a local chain of Seattle. In 2001, she replaced Joan Roberts as Heidi Schiller in the revival of the musical Follies by Stephen Sondheim and in 2003 returned to Broadway to both interpret the role of Guido’s mother in a revival of Nine. In the Disney film Mulan 1998, Marni Nixon sang the songs of the role of Grandmother Fa. In March 2007 she participated in a version of My Fair Lady concert where he played the role of Mrs. Higgins. Subsequently performed this role replaces Sally Ann Howes in the U.S. tour of Cameron Mackintosh’s West End revival of My Fair Lady in July 2008. Published under his name has recorded songs by Jerome Kern, George Gershwin, Arnold Schoenberg, Charles Ives and Anton Webern.