In 1983 Mattila graduated from the Sibelius Academy in Helsinki, where she studied singing with Liisa Linko-Malmio. She then continued her studies with Vera Rozsa in London.\r \r Also in 1983, Mattila won the first Cardiff Singer of the World competition. In 1985, she made her Covent Garden debut with the Royal Opera as Pamina in Mozart's Die Zauberflöte.\r \r She was seen as Emma in the first ever televised production of Schubert's Fierrabras at the Vienna State Opera in 1988. In 1990 she made her Metropolitan Opera debut as Donna Elvira in Mozart's Don Giovanni. In 1994, she made her Spanish debut as Tatyana in Tchaikovsky's Eugene Onegin in Madrid, and 1996 debuts in Paris in Wagner's Lohengrin, Verdi's Don Carlos.\r \r Mattila has won Grammy Awards for "Best Opera Recording" for Die Meistersinger von Nürnberg in 1998 and for Jenůfa in 2004. She was awarded the Evening Standard Ballet, Opera and Classical Music Award for “Outstanding Performance of the Year” in 1998 for her performance of Elisabeth in Don Carlos at the Royal Opera House. In 2001 The New York Times chose Karita Mattila as the best singer of the year for her performance in Fidelio at the Metropolitan Opera, and in the same year she was nominated for the Laurence Olivier Award “Outstanding Achievement in Opera”.\r \r Mattila's 2004 New York performances in Salome and subsequent Káťa Kabanová inspired the New York press to write: "When the history of the Metropolitan Opera around the time of the millennium is written, Karita Mattila will deserve her own chapter."\r \r In 2005, she was named Musician of the Year 2005 by Musical America, which describes her "the most electrifying singing actress of our day, the kind of performer who renews an aging art form and drives the public into frenzies." BBC Music Magazine named Mattila as one of the top 20 sopranos of the recorded era in 2007.\r \r Worldwide audiences saw Mattila in Manon Lescautlive in movie theatres in 2008. Metropolitan's Salome and Tosca were seen live in High Definition worldwide in 2008 and 2009, respectively.\r \r In 2010 at Opéra National de Lyon, Mattila created the role of émilie du Chatelet in Kaija Saariaho's monodrama émilie, which was dedicated to her.