Lupu was born in Galaţi, the son of Meyer Lupu and Ana Gabor. He started to learn the piano as a 6-year old (with Lia Busuioceanu), making his public debut at age 12. After completing high school in Galaţi, and graduating from the Popular School for the Arts in Braşov, Lupu continued his studies at the Bucharest Conservatory with Florica Musicescu and Cella Delavrancea. In 1961, he was awarded a scholarship to the Moscow P.I. Tchaikovsky State Conservatory, where he studied with Galina Eghyazarova, Heinrich Neuhaus, and Stanislav Neuhaus.
He resides in Lausanne, Switzerland.
Lupu's concert appearances, though not frequent, are consistently acclaimed. Trained in the Russian pianistic tradition, he is particularly noted as an interpreter of the great 19th century German and Austrian composers, especially Franz Schubert, Johannes Brahms, Ludwig van Beethoven, and Wolfgang Amadeus Mozart, although he is also noted for performances of works by Czech composer Leos Janácek, as well as Hungarian composer Béla Bartók.