Lone Koppel was born in Copenhagen in 1938, the daughter of the pianist and composer Herman D. Koppel and his wife Vibeke. Following private lessons with Aksel Schiøtz, in 1955 Lone Koppel was admitted to the Royal Danish Academy of Music as the pupil of Professor Dora Sigurdsson, and later to the Danish Opera Academy. She made her debut in 1961, having already sung the soprano part in Verdi's Requiem in Sweden. Her debut at the Royal Danish Opera in Copenhagen in 1962 was as Musetta in La Bohème. She was attached to the opera in Kiel 1964-66, during the same period appearing as guest artist at the Royal Danish Opera. In 1987, she celebrated her 25th jubilee as Elektra and, in 2002, her 40th jubilee as the Countess in Queen of Spades. She has given guest performances in the Scandinavian opera houses: Stockholm, Gothenburg, Helsinki and Oslo, as well as in Germany, England, the Netherlands and New Zealand. From 1973 to 1978 she was permanent member of the Australian Opera in Sydney, where she continued to give guest performances until 1999.
Her repertoire included the dramatic soprano parts by Verdi and Wagner and Richard Strauss: Lady Macbeth in Macbeth, Abigaille in Nabucco, Amelia in Un Ballo in Maschera, Elisabetta and Eboli in Don Carlo, Amneris in Aida as well as Kundry in Parsifal, Senta in Der fliegende Holländer, Ortrud in Lohengrin, Elisabeth and Venus in Tannhäuser, Salome, Elektra and Ariadne in Ariadne auf Naxos. She was especially famous for her interpretation of Puccini's Tosca, which was preserved in a TV-production 1964.
Lone Koppel has sung solo parts in the concert and oratorio repertoire and has sung a great number of lied concerts with her father Herman D. Koppel. For many years she has taught at the Danish Opera Academy. As a director, in 1993 she staged Peter Heise's opera Drot og marsk (King and Marshal) at the Royal Danish Theatre, and in 2003 she staged Verdi's Nabucco at the Värmland Opera in Karlstad in Sweden.