Born in Găujani, Giurgiu County, she studied violin at the Music High School in Brașov and voice at the Music Conservatory in Cluj-Napoca, before winning a scholarship at the Conservatorio di Santa Cecilia in Rome to be taught canto by Jolanda Magnoni; she also worked with Rodolfo Celletti and Elisabeth Schwarzkopf. Upon graduation, in 1972, having won the Voci Rossiniane Competition in Milan, American conductor Thomas Schippers invited her to Cincinnati as Mimì in Puccini's La Bohème and later she was invited by Luchino Visconti to appear in Don Carlos at the Teatro dell'Opera di Roma. She made her debut at the Metropolitan Opera in New York City, in 1978, as Violetta in Verdi's La traviata, a role she has reprised over 200 times, later singing Gilda in Verdi's Rigoletto (1978) and Nedda in Leoncavallo's I Pagliacci (1978-1986). She sang in the worlds major opera houses such as Teatro alla Scala in Milan, where she had her debut in the world première of Luciano Berio's La Vera Storia (1982) and later appeared in: The Stone Guest (Donna Anna) by Dargomyzhsky (1983), Lucio Silla (Cinna) by Mozart (1984), Polish Requiem by Penderecki (1985), L'Orfeo (Euridice) by Luigi Rossi (1985), Un re in ascolto (La Protagonista) by Berio (1986), Don Giovanni (Donna Elvira) by Mozart (1987, 1988, and 1993), Fetonte (Queen Climene) by Jommelli (1988), Alcyone and Alyssa by Ravel (1990) and three Recitals (1988, 1993). Mariana Nicolesco interpreted a wide repertory from baroque, belcanto to verismo and contemporary music and has been described as "an arresting personality with a vibrant voice"; highlights of her repertory are the roles of Marzelline in Fidelio by Beethoven, Elettra in Idomeneo, Vitellia in La clemenza di Tito by Mozart, Beatrice di Tenda by Bellini, Anna Bolena, Maria Stuarda, Queen Elisabeth I in Roberto Devereux, Maria di Rohan by Donizetti, Amelia in Simon Boccanegra, Desdemona in Otello, Leonora in Il trovatore, Luisa in Luisa Miller by Verdi, Marguérite in Faust by Gounod, Tatyana in Evghenij Oneghin by Tchaikovsky, Liù in Turandot by Puccini, Zarina Marina in Dimitry by Dvořák. She appeared in productions signed by Giorgio Strehler, Patrice Chéreau, Luca Ronconi, Jean-Pierre Ponnelle, Franco Zeffirelli, Pier Luigi Pizzi, Jonathan Miller and conducted by Carlo Maria Giulini, Wolfgang Sawallisch, Riccardo Muti, Seiji Ozawa, Lorin Maazel, Peter Maag, Georges Prêtre, Giuseppe Patané, Alberto Zedda, Colin Davis, Ghennadij Rozhdestvensky; also in prestigious Concerts Halls such as Carnegie Hall in New York, Royal Festival Hall in London, Accademia di Santa Cecilia in Rome, Concertgebouw in Amsterdam, Musikverein in Vienna, Salle Pleyel in Paris, the Great Conservatory Hall in Moscow and the Salzburg Festival, Rossini Opera Festival in Pesaro, Maggio Musicale Fiorentino, Martina Franca Festival, Casals Festival in Puerto Rico. Invited by Pope John Paul II, she sang Romanian Carols in the First Christmas Concert in the Vatican (1993) and the soprano part in the world première of Krzysztof Penderecki's Symphony No. 7 (Seven Gates of Jerusalem) was composed for her (1997).
She returned to Romania in 1991, after the fall of the Communist regime, singing for the first time on a stage in her native country, in a Concert at the Romanian Atheneum in Bucharest. As some 10,000 tickets were purchased, Nicolesco gave three consecutive performances. She created the Romanian Atheneum International Foundation and donated in 1994 a Steinway grand concert piano. In 1995, Mariana Nicolesco initiated the Hariclea Darclée International Voice Competition and Festival. In the years between an edition of the Contest and the next, she offers Master Classes to the young artists. She obtained for the Darclée events the High UNESCO Patronage. In 2003, she created the Romanian National Festival and Song Competition and presented for the International George Enescu Year, proclaimed by UNESCO (2005), in world première the composer's complete songs in Japan, at Aichi World Exhibition as well as in Nagoya and Tokyo, in Prague, Paris, Rome and New York City. In 2014 she is a Member of the Jury of China International Vocal Competition with 430 competitors from 41 countries.
An Honorary Member of the Romanian Academy since 1993, Officer of the Order of the Arts and Letters in France (2000), Ph.D. and Doctor Honoris Causa of the Gheorghe Dima Music Academy in Cluj-Napoca (1996), she was awarded the Order of the Star of Italian Solidarity (2004) and the Order of the Star of Romania, in the Rank of Grand Cross (2008). She was also named UNESCO Artist for Peace (2005), UNESCO Goodwill Ambassador, elected the Most Successful Woman in Romania (2004) and was conferred the Special Award Kultur Preis Europa Medal in Sibiu, European Capital of Culture (2007). She is a Honorary Citizen of Bucharest (1991),  Cluj Napoca (1994), Braila (1995), Brasov (1999). Nicolesco is married to art critic and art historian Radu Varia.
|1981||Meyerbeer: Gli amori di Teolinda (cantata)||—||Nicolesco||Wolfgang Gönnenwein
Ludwigsburg Festival Orchestra
|1983||Puccini: La rondine||Lisette||Te Kanawa
Nucci, et al.
London Symphony Orchestra
|1987||Bellini: Beatrice di Tenda||Beatrice di Tenda||Nicolesco,
La Scola, et al.
Monte-Carlo Philharmonic Orchestra
Sony 1995, 2009
|1987||Mozart: The Marriage of Figaro||Marcellina||Hynninen
Nicolesco, et al.
Vienna Philharmonic Orchestra
|1987||Ravel: Alyssa and Alcyone (cantatas)||—||Nicolesco,
|1988||Donizetti: Maria di Rohan||Maria||Nicolesco,
Franci, et al.
|Massimo de Bernart
Orchestra Internazionale d'Italia
|1990||Verdi: Simon Boccanegra||Maria Boccanegra||Bruson
Scandiuzzi, et al.
Tokyo Symphony Orchestra
- Oxford Music on line
- (Romanian) Magdalena Popa Buluc, "Mariana Nicolesco: 'Trăiesc într-un perpetuu foc de artificii'" ("Mariana Nicolesco: 'I Live in a Continuous Fireworks Display'"), Cotidianul, 25 July 2010; accessed March 17, 2012
- New York Metropolitan Opera Archives on line
- Teatro alla Scala Archivio on line
- (Romanian) Corina Stoica, “Mariana Nicolesco: Sunt prea spontană, prea directă ca să spun minciuni” (Mariana Nicolesco: I am too spontaneous, too direct, therefore incapable to lie)[permanent dead link], "Revista Tango", September 15, 2010
- (Romanian) Cezarina Adamescu „O mie de voci într-o singură voce: Mariana Nicolesco omagiu primei doamne a lirice româneşti" (A thousand voices in one: Mariana Nicolesco homage to a First Lady of Opera)  „Confluenţe româneşti", October 26, 2011
- (Romanian)„Colinde cu Mariana Nicolesco la Vatican“ (Carols with Mariana Nicolesco at the Vatican), "Evenimentul zilei", December 24, 2011
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- (Romanian) Costin Popa “Festivalul şi Concursul de Canto Darclée – Nicolesco, o sărbătoare!” (Festival and Voice Contest Darclée – Nicolesco, a feast!) "Cultura", August 26, 2010
- (Romanian) „Omul zilei: Mariana Nicolesco” (Woman of the day: Mariana Nicolesco), "Jurnalul Naţional", August 1, 2011
- (Romanian) “Regina Mariana Nicolesco, încoronată” (Queen Mariana Nicolesco crowned, “Evenimentul zilei”, August 21, 2012
- (Romanian)“O coroana pentru trei Regine: Hariclea Darclee, Maria Callas, Mariana Nicolesco” (A crown for three Queens: Hariclea Darclee, Maria Callas, Mariana Nicolesco), “Revista VIP”, August 27, 2012
- (Romanian) „Mariana Nicolesco a obţinut înaltul patronaj al UNESCO pentru evenimentele Darclée din România” (Mariana Nicolesco obtained for the Darclée events in Romania the High UNESCO Patronage) Mediafax, July 9, 2014
- (Romanian) Simona Suciu “Festival marca Mariana Nicolesco, la Braşov” (A Festival label Mariana Nicolesco in Brasov) "Adevărul", October 26, 2011
- (Romanian) „Mariana Nicolesco, întâmpinată ca un star în China” (Mariana Nicolesco, received like a Star in China) Evenimentul zilei, November 28, 2014
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- (Romanian) Mariana Nicolesco Doctor  Gheorghe Dima Academy of Music Cluj-Napoca
- (Romanian) Mariana Nicolesco Doctor Honoris Causa  Gheorghe Dima Academy of Music Cluj-Napoca
- Sito web del Quirinale: dettaglio decorato. Archived 2013-11-10 at the Wayback Machine.
- (Romanian) Comunicat de Presă (Press release)  Presidency site, December 1, 2008
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- "Archived copy". Archived from the original on 2013-07-03. Retrieved 2013-07-17.
- (Romanian) "Mariana Nicolesco, Ambasador Onorofic UNESCO, la Reuniunea de la Paris: Nimic nu-i poate apropia pe oameni mai mult decât cântul" (Romanian soprano Mariana Nicolesco, UNESCO Goodwill Ambassador: Nothing can bring people closer than singing) "Cotidianul", July 2, 2013
- (Romanian) "50 de românce cu succes şi bani" (50 successful rich Romanian women)  "Jurnalul Naţional", March 31, 2004
- "Mariana Nicolesco ausgezeichnet" (Mariana Nicolesco awarded)  Kultur Forum Europa site
- ″Mariana Nicolesco Cetatean de Onoare Bucuresti″ Archived 2013-04-03 at the Wayback Machine.
- ″Mariana Nicolesco Cetatean de Onoare Cluj Napoca″
- ″Mariana Nicolesco Cetatean de Onoare Braila″
- ″Mariana Nicolesco Cetatean de Onoare Brasov″
- (Romanian) Loredana Oprea, "Un ieşean, medaliat de Academia Regală din Scoţia", Ziarul de Iaşi, 5 December 2011; accessed March 14, 2012
- Hariclea Darclee Festival and International Voice Competition
- "Soluţia Mariana Nicolesco" (Mariana Nicolesco: The Solution
- "Interviu cu celebra soprană Mariana Nicolesco: Într-o lume a violenței și a declinului valorilor îi admir pe tinerii care-și dedică viața cântului (Interview with the celebrated soprano Mariana Nicolesco: in a world of violence and decline of all values I admire the young artists who devote their lives to the art of singing)
- "Secundatv deschide rubrica Interviuri Stelare cu Diva Divină Mariana Nicolesco" (Secundatv opens Stellar Interviews with Diva Divine Mariana Nicolesco)
- "Mariana Nicolesco mărturii senzaționale despre arta cântului" (Mariana Nicolesco's sensational thoughts and testimonials about the art of singining)