Born in Bedford, England, Nicholls studied French at the University of York, and from 1998 voice at the Royal College of Music with Kathleen Livingstone.
[6] She returned to Covent Garden to sing Prilepa in Tchaikowsky's Queen of Spades, Pepik in Janáček's The Cunning Little Vixen and Echo in Strauss's Ariadne auf Naxos.
She performed First Woman – First Fury in Birtwhistle's The Mask of Orpheus: The Arches at the BBC Proms, Nerone in Monteverdi's L'incoronazione di Poppea at the New Theatre, Tokyo, Tatyana in Tchaikowsky's Eugene Onegin for Scottish Opera, Jenifer in Tippett's The Midsummer Marriage, Sieglinde in Wagner's Die Walküre and Anne Trulove in Stravinsky's The Rake's Progress at the St Endellion Festival.
[2] Fiona Maddocks reviewed Götterdämmerung in The Observer: "Longborough has found a magnificent Brünnhilde in Rachel Nicholls, a singer so versatile that she has also had a career as a Bach specialist.
[10] In a 2007 recording of Bach's Mass in B minor, conducted by Suzuki, she appears with Carolyn Sampson, Robin Blaze, Gerd Türk and Peter Kooy.