KT Sullivan starred with Steve Ross in The Irish Rep’s virtual presentation of “Love, Noël” after a sold-out run in the summer of 2019. In 2022, KT began singing and playing every Tuesday in the lobby of The Algonquin Hotel and has been extended through 2024. KT was named artistic director of The Mabel Mercer Foundation in 2012. She starred in the Broadway revival of, and headlined for almost two decades in The Oak Room of The Algonquin Hotel. One of the shows she created there, Rhyme, Women, and Song  was presented on PBS’ WNET 13 and her award winning Sondheim show with Jeff Harnar was filmed for PBS from the New Jersey Performing Arts Center.​

Besides regular appearances in such New York venues as The Laurie Beechman Theatre and Birdland, she has starred annually at The Pheasantry in London, and has been showcased at Lincoln Center, Carnegie Hall, The Kennedy Center, Spoleto Festival, Chichester Festival, CLUB RaYé in Paris, and The Adelaide Festival in Australia.

She guest starred on Garrison Keillor’s Prairie Home Companion, recorded six albums on the DRG Label, was the star vocalist on two tours of China with The Manhattan Symphonie. Miss Sullivan was twice named one of The Top 100 Irish Americans by Irish America Magazine and was married for 22 years to Stephen Downey, president of The New York Browning Society.

​Her Broadway credits include Gentlemen Prefer Blondes, Three Penny Opera (w/Sting), and Broadway as  Katie (George Abbott, Dir.). Off Broadway, she appeared in A…My Name Is Alice, Splendora, and American Rhapsody (w/Mark Nadler). Her National Tour credits include Annie Get Your Gun (w/Cathy Rigby), and her Regional Theater credits are Missouri Rep, Hartford Stage Company, Great Lakes Theater, Long Wharf Theatre, Paper Mill Playhouse. On television she appeared in Police Squad (w/Leslie Nielsen), Remington Steele, Night Court, Rhyme, Women & Song (PBS’ WNET 13), Stephen Sondheim Show w/Jeff Harnar (PBS’ NJPAC), In Performance at The White House (PBS). She has appeared in many concerts and festivals including at The Town Hall, Lincoln Center, Kravis Center (Palm Beach), Chichester Festival (England), Adelaide Festival (Australia), Corpus Christi Symphony (Kurt Weill’s Seven Deadly Sins), Two Tours of China with The Manhattan Symphonie. Her many cabaret and jazz clubs appearances include Birdland, The Laurie Beechman Theatre, The Beach Cafe, The Green Room 42, The Oak Room of The Algonquin, Café Sabarsky (Neue Gallerie), The Pheasantry (London), and La Nouvelle Eve (Paris).