Royal was born in London in 1979. Her father wrote and sang songs for TV in the 1970s, while her mother was a model and dancer who ran her own studio, so it was assumed that either Kate or her sister would end up performing for a living. Royal was introduced to classical music in high school and found it suited her voice better than the songs of musical theater. She attended the Guildhall School of Music and Drama and the National Opera Studio. It wasn't long after graduating and winning the 2004 Kathleen Ferrier Award that others began to see her talent. She was an understudy at Glyndebourne and a member of its touring company, singing Mozart and Britten in those couple of years before she signed an exclusive contract with EMI in the fall of 2006. Her self-titled solo debut recording -- featuring songs and arias by Debussy, Stravinsky, Rodrigo, and others, and backed by the Academy of St. Martin in the Fields -- was released in 2007. Since then, she has been a part of Graham Johnson's Schumann series, the tenth volume, on Hyperion, a featured artist on Ian Bostridge's Great Handel album, and released two more solo discs: Midsummer Night (2009) and A Lesson in Love (2011).
As for her live performances, Royal has appeared on-stage and in choral performances with conductors such as Simon Rattle, Myung-Whun Chung, and Yannick Nézet-Séguin. Her roles have included Marschallin in Der Rosenkavalier, Pamina in Die Zauberflöte, Miranda in The Tempest, Handel oratorios, and Mahler symphonies. In 2015, Royal was heard on the collection Karl Jenkins: Voices. She joined the Milwaukee Symphony Orchestra, under William Boggs, in 2018 for a Florentine Opera production of Carlisle Floyd's Prince of Players; a recording of this production was issued in 2020. Royal sets aside five months of every year to do song recitals. She has learned that structuring her work this way gives her the time she needs to fully prepare for opera roles and to focus on her family. ~ Patsy Morita, Rovi