Ruth Ziesak studied at the Academy of Music and Performing Arts in Frankfurt am Main under Elsa Cavelti. Numerous competition successes, including the first prizes at the Deutscher Musikwettbewerb and the renowned International Vocal Competition 's Hertogenbosch, quickly paved the way for an international career. Meanwhile she has also been appointed a Professor of Singing at the Saar Academy of Music.

After early appearances at the Theater Heidelberg and the Deutsche Oper am Rhein Düsseldorf/Duisburg, she went on to sing on the international stages in Munich, Milan, Berlin, Florence, Vienna, Paris, London and New York, where she made a name for himself in her signature roles of as Pamina, Ännchen, Marzelline, Ilia and Sophie. She has since broadened her repertoire, and has appeared as the Countess in Le Nozze di Figaro in Glyndebourne and Zürich, and in 2010 at the Stuttgart Opera under Manfred Honeck.

The multifaceted artist is also much in demand as a concert singer, and enjoys working with such Baroque orchestras as the Akademie für Alte Musik Berlin or the Freiburger Barockorchester. She makes frequent guest appearances at the Salzburg Festival and the Lucerne Festival. Her work with conductors such as Herbert Blomstedt, Daniele Gatti, Riccardo Muti, Kent Nagano, Lothar Zagrosek, Riccardo Chailly, Jukka Pekka Saraste and Ivor Bolton has taken her to the Gewandhausorchester Leipzig, the Staatskapelle Dresden, the Bavarian Radio Symphony Orchestra, the WDR Symphony Orchestra, the Konzerthausorchester Berlin, the Montreal Symphony Orchestra and the Mozarteum-Orchester in Salzburg.

Most recently, Ruth Ziesak appeared with the Los Angeles Symphony Orchestra and the Berlin Philharmonic, on both occasions under Herbert Blomstedt with Beethoven's Missa solemnis, at the Orchestre National de France in the Salle Pleyel in Paris under Christoph Eschenbach (Brahms Requiem), with Schumann's Scenes from Faust with the Frankfurt Museums-Orchester under Sebastian Weigle, and with the Vienna Philharmonic under Leopold Hager in Rome. In 2014 she appeared with the Orquesta sinfonica RTVE in Madrid and with the Orquesta di Valencia, on both occasions under Yaron Traub with Poulenc's Stabat mater, with the Scottish Chamber Orchestra, again under E. Krivine, with the Czech Philharmonic in Prague with Haydn's Creation and at the Lucerne Festival under Sir Andras Schiff with Beethoven's Missa solemnis.

The current season is taking Ruth Ziesak to concerts with the Philharmonischer Chor Berlin and Jörg Peter Weigle in Berlin (Max Bruch/Das Lied von der Glocke), the Auryn Quartet and Gerold Huber in Bilbao, and the Bamberg Symphony Orchestra and the San Francisco Symphony Orchestra, on both occasions under Herbert Blomstedt (Brahms/A German Requiem). In December she is on tour with a programme of Baroque music in the company of Reinhold Friedrich and the Philharmonie Reutlingen conducted by Aurélien Bello. In Vicenza she is singing Haydn's Theresienmesse and Johannes Brahms's Zigeunerlieder with Sir Andras Schiff conducting at the piano. She is closing the season in Vienna with the city's Radio Symphony Orchestra conducted by Cornelius Meister (Bruckner/F minor Mass).

As a lieder singer she is regularly accompanied by the pianist Gerold Huber, with whom she appeared in Vienna, Berlin, London, at the Heidelberger Frühling and the Kissinger Sommer. Ruth Ziesak is among Sir András Schiff's regular lieder partners. They appeared together at London's Wigmore Hall, at the Salzburg Festival and at the Philharmonie in Berlin. In the field of chamber music, she works together with the Merel Quartet, the Vienna Piano Trio, the Auryn Quartet and the Trio Wanderer.

Alongside her concert recordings with Sir Georg Solti, Riccardo Chailly and Herbert Blomstedt for Decca, Ruth Ziesak has recorded The Magic Flute (Solti/Decca), Fidelio (von Dohnànyi/Decca), La Clemenza di Tito (Harnoncourt/Teldec), Der Freischütz (Janowski/BMG), Hansel and Gretel (Runnicles/Teldec) and Robert Schumann's Genoveva with the Chamber Orchestra of Europe (Harnoncourt/Teldec). Among her solo recordings are operatic arias with the Deutsches Symphonie-Orchester Berlin under Marcus Creed (Capriccio) and lieder by Mahler (Gatti/BMG), as well as a series of lieder recitals for BMG, Naxos and Sony with Ulrich Eisenlohr. Among her CD recordings are Mendelssohn's Elijah and his Lobgesang Symphony (MDR Symphony Orchestra /Jun Märkl/Naxos). Following her solo CDs of Liszt lieder (edel classics), Haydn canzonettas and lieder (Phoenix) and Mendelssohn lieder (AVI), Phoenix have released a recording of Mahler und Zemlinsky lieder, all accompanied at the piano by Gerold Huber.