For over twenty years she enjoyed, and cherished, a fantastic relationship with the renowned vocal coach and pianist, David Harper - an artist to whom she credits many of her most successful performances. It was the bel canto repertoire and her dedication to rediscovering forgotten operas where Nelly found her niche. Universally acclaimed for her luscious sound, beautifully constructed technique and exceptional theatrical stage presence, Michael Davdison wrote about her in an article in Opera Magazine: "The highly individual timbre of Miricioiu’s voice, her imagination and intensity, her exceptional range and sense of timing make for a unique talent. "

Born in Adjud, Romania, Nelly started singing at 5 and was hailed as a child prodigy. At 9 she started studying piano and at 14 won her first singing contest, Young Talents, Great hopes. At 18 she sang in Pergolesi's La serva padrona and joined the Conservatory in Iasi, where she continued her studies with Tibi Popovici. In 1972 she was the youngest contestant in the Francisco Vinas Musical Competition in Barcelona, winning Second Prize (no First prize was awarded), and in 1975 she won First Prize at the very first Maria Callas Grand Prix in Athens.

More 1st prizes followed at competitions in Geneva, Paris, Sofia, Oostende etc.

Nelly made her professional operatic debut with a return toPergolesi's La Serva Padrona, and as Papagena in Mozart's The Magic Flute at Iasi Opera House, and continued to sing at Brasov Opera House between 1975-1978 in roles such as Mimi in La boheme, Micaela in Carmen and Rosalinde in Die Fledermaus.

In 1996 she was trusted with the revival of the infamous Tosca production for Maria Callas. The revival was a huge success and established her as one of the best Tosca's seen on stage. Clive Hirshon wrote in the Daily Express: "Nelly Miricioiu had the requisite passion for the title role plus a melting pianissimo that ravished the house with its purity of tone." while The Financial Times' Richard Fairman wrote: "her Tosca is an artist down to her fingertips, the kind who turns every wave in a theatrical event". She reprised her appearance as Tosca on the Royal Opera House stage in 2001, and in 2003 enjoyed an immense success as Elisabetta in Roberto Devereux by Donizetti -

of which a recording was later released by Opera Rara: "it was Miricioiu's opera, and ultimately her evening. Hers was the longest role and the most demanding, not merely in its manifold technical difficulties but in its range of mood - suspicion, hope, love, hate, joy, pride and finally a bitter, crazed fury. All of these require expression, both in the enunciation of Cammarano's text and in the vocalising of Donizetti's taxing music. Even the greatest bel canto exponents might experience mishaps over such a long ordeal, but Miricioiu's diligent connection to words, music and meaning held out to the end in singing of outstanding consistency and command." (George Hall - Opera News)