Early life 
Coertse, born in Durban, KwaZulu-Natal, matriculated at the Helpmekaar Girls High School in Johannesburg. She began vocal studies in South Africa in 1949. In July 1953 she married the broadcaster and composer Dawid Engela. She left South Africa in September 1953 for London, and then went via The Hague to Vienna. In January 1954 she started training with Maria Hittorff and Josef Witt.
Opera career 
Coertse made her debut in January 1955 as the First Flower girl in Wagner's Parsifal at the Teatro San Carlo in Naples, Karl Böhm conducting. She also sang in Basle at the Teatro San Carlo. On 17 March 1956 she made her debut at the Vienna State Opera as the Queen of the Night in Die Zauberflöte by Mozart and remained with the Vienna State Opera until 1978. Her Covent Garden debut was in 1956, in the same role.
Coertse sang the soprano part in Bach's Matthäus-Passion at Fritz Wunderlich's first appearance in Vienna in 1958, when he performed the tenor arias with Julius Patzak singing the Evangelist. In 1958, Coertse and Fritz Wunderlich again worked together at the Aix-en-Provence festival in Die Zauberflöte. In 1965, she sang Konstanze in Die Entführung aus dem Serail at the Vienna State Opera which also featured Fritz Wunderlich as Belmonte.
Her repertoire also includes:
- The Magic Flute (Wolfgang Amadeus Mozart) - Queen of the night
- Il Seraglio (Wolfgang Amadeus Mozart) - Constance
- Ariadne auf Naxos (Richard Strauss) - Najade, later Zerbinetta
- Rigoletto (Giuseppe Verdi) - Gilda
- The Tales of Hoffmann (Jacques Offenbach) - Olympia, Antonia, Giulietta, Stella
- Palestrina (Hans Pfitzner) - the Angel
- Carmen (Georges Bizet) - Frasquita
- Martha (Friedrich von Flotow) - Martha
- Mignon (Ambroise Thomas) - Philine
- La traviata (Giuseppe Verdi) - Violetta
- An Irish Legend (Werner Egk) - female lead
- Unverhofftes Begegnen (Joseph Haydn) - female lead
- I Pagliacci (Ruggiero Leoncavallo) - Nedda
- Arabella (Richard Strauss) - Fiaker-Milli
- Bastien und Bastienne (Wolfgang Amadeus Mozart) - Bastienne
- The Merry Widow (Franz Lehár) - Hanna Glawari
- Lucia di Lammermoor (Gaetano Donizetti) - Lucia
- Die Fledermaus (Johann Strauss II) - Rosalinde
- L'heure espagnole (Maurice Ravel) - Concepcion, staging Otto Schenk
- Don Giovanni (Wolfgang Amadeus Mozart) - Donna Elvira
- La bohème (Giacomo Puccini) - Musetta
- Norma (Vincenzo Bellini) - Norma
- Così fan tutte (Wolfgang Amadeus Mozart) - Fiordiligi
- Falstaff (Giuseppe Verdi) - Mrs. Alice Ford
- Turandot (Giacomo Puccini) - Liu, a young slave
- Angelique (Jacques Ibert) - Angelique, staging Axel Corti
- Don Giovanni (Wolfgang Amadeus Mozart) - Donna Anna
- Die schweigsame Frau (Richard Strauss) - Aminta, Timida 1968 Premiere Vienna State Opera, staging Hans Hotter
- Die ägyptische Helena (Richard Strauss) - Aithra
- Daphne (Richard Strauss) - Daphne
- Don Carlos (Giuseppe Verdi) - Elisabeth von Valois
Coertse has sung in theatres at Aix-en-Provence, Athens, Barcelona, Brussels, Covent Garden, Düsseldorf, Glyndebourne, Graz, Hamburg, Linz, London, Melk, Naples, Palermo, Salzburg, Stuttgart, The Hague, Turin and Wiesbaden and with conductors like Karl Böhm, Vittorio Gui, Alberto Erede, Heinrich Hollreiser, Herbert von Karajan, Joseph Keilberth, Jascha Horenstein, Rudolf Kempe, Josef Krips, Rafael Kubelík, Erich Leinsdorf, Wilhelm Loibner, Lorin Maazel, Dimitri Mitropoulos, Edouard van Remoortel, Rudolf Moralt, Heinz Wallberg, Nello Santi, Giuseppe Patane, John Pritchard, Argeo Quadri, Mario Rossi, Sir Malcolm Sargent, Hermann Scherchen, Georg Solti, Hans Swarowsky, Horst Stein, George Szell, Silvio Varviso, Antonino Votto and Berislav Klobučar.
Among the famous singers who have partnered her were Eberhard Wächter, Jean Madeira, Giuseppe di Stefano, Alfredo Kraus, George London, Walter Berry, Rudolf Christ, Renate Holm, Boris Christoff, Anton Dermota, Otto Edelmann, Cesare Siepi, Giuseppe Taddei, Ettore Bastianini, Luciano Pavarotti, Aldo Protti, Simon Estes, Hilde Gueden, Johannes Heesters, Sena Jurinac, Waldemar Kmentt, Peter Schreier, Gottlob Frick, Paul Schöffler, Erich Kunz, Christa Ludwig, Julius Patzak, Murray Dickie, Luigi Alva, Helge Rosvaenge, Rudolf Schock, Birgit Nilsson, Teresa Stich-Randall, Gwyneth Jones, Otto Wiener, Heinz Holecek and Giuseppe Zampieri.
She is also well known in South Africa for Afrikaans art songs.
Later years 
Since returning to South Africa in 1973 she has been a regular guest on South African stages and also a frequent broadcaster on radio and television. In recent years she has devoted her time to exposing young South African singers to the neglected art of Lieder singing which can be artistically even more demanding than opera singing. Her support for her fellow South African musicians has been outstanding - as may be witnessed in her Debut with Mimi and through the Mimi Coertse Bursary.
In 1998 Mimi Coertse and Neels Hansen founded The Black Tie Ensemble, a development project which enables young, classically trained singers to bridge the gap between training and professional performance. This project has developed into the most exciting classical singing ensemble in South Africa, and is now on the brink of becoming a vibrant, new, young opera company. A project for future stars of Africa! The Ensemble, sponsored by Sappi, performs operas at the State Theatre (Pretoria), Walter Sisulu Botanical Gardens (Johannesburg) and the Civic Theatre (Johannesburg).
Honours and awards 
- 1961: Medal of Honour of the South African Academy for Science and Art (Suid-Afrikaanse Akademie vir Wetenskap en Kuns
- 1966: Title of Kammersängerin
- 1985: Decoration for Meritorious Services (South Africa) in recognition of her contribution to the Arts
- August 1996: Austrian Cross of Honour for Science and Art
- 2002: Golden "Rathausmann"
- 2003: Honorary Doctor of Philosophy (h.c.) from the University of Pretoria, South Africa
- In 2004: Voted 45th in the Top 100 Great South Africans
- In 2008: Mimi Coertse Museum van Afrikaans opened at Huis vir Afrikaanse Poësie in Capital Park, Pretoria.
- 2012: 1. July - 30. Sept. Special exhibition in Staatsoper museum Vienna: "Mimi Coertse, a Viennese woman from South Africa"
"Vienna, March 1996
My beloved Mimi!
Can you still remember the 17th March 1956, exactly forty years ago, when you came completely excited into my room in the Viennese Opera, and said to me with a trembling voice: "Just imagine, Böhm asked me to stand in as QUEEN OF THE NIGHT this evening. Rita Streich got suddenly sick and had to call off. My debut should have been later in the Viennese house and now I have to stand in for one of the most wonderful Queens of the Night! Please, keep your fingers crossed for me. I have sung this part very often; but, as a stand-in and even a début… Oh God!" Of course, I saw the performance, of course, I crossed my fingers for her and – to cut a long story short, that evening Vienna found a new opera-favourite - MIMI COERTSE - and you got a contract at the Viennese Opera!
That happened forty years ago. You have sung many, many parts in the following nearly two decades. Unforgettable are your parts as GILDA, TRAVIATA, OLYMPIA, CONSTANCE, DONNA ELVIRA and DONNA ANNA, NEDDA, ZERBINETTA, FIAKER-MILLI, LUCIA DI LAMMERMOOR and the "SPANISH HOUR", and also your "MERRY WIDOW", which you have sung more than one hundred times with Johannes HEESTERS in the "Redoutensaal". When I was in your home country a few years ago I saw you sing the part of the FIGARO COUNTESS in PRETORIA, and time seemed to have stood still. The beauty of your voice has not changed and the timbre was as fascinating as ever - I came to see FIGARO six times! A few days ago I met a friend of ours who told me that he had heard you sing in a POP-CONCERT in Cape Town! You were absolutely wonderful.
In 1966 you were appointed AUSTRIAN CHAMBER SINGER (Kammersängerin). At that time I ran the so-called "’Ordenskanzlei’ (honours committee) of the federal theatres" and wrote the application of the Viennese State Opera to the Austrian President as follows: "Mrs. Coertse is one the most important members of the ensemble, not only because of her extremely beautiful and cultivated voice, her exemplary technique and, above all, her attractive appearance on stage but also because of her absolute reliability and constant devotedness." On 5 October 1966 the former Minister of Education and Culture, Dr. Theodor PIFFL-PERCEVIC, presented the decree to you during a very warm and beautiful celebration.
Dear Mimi, when I think back to all those years, vivid memories of all the happy but also sometimes sad days come to my mind. You have become one of the greatest artists but also one of the loveliest and most faithful persons. You were always dependable concerning art but also concerning friendship with me."
"Mimi Coertse: I have pleasant memories of your distinctive timbre and your sweet but never too sentimental voice. This voice could convey situations, fates of women, and feelings in a realistic way: when MIMI COERTSE sang and acted the distraction of LUCIA, the despair of NORMA, the grief of KONSTANZE, the threatening doll-like appearance of OLYMPIA or the fear of death of VIOLETTA VALERY, the audience was deeply moved. Also the part of NEDDA, the FIAKERMILLI, GILDA and DONNA ANNA... and and and...I find myself discovering more and more roles that MIMI COERTSE sang at the Vienna State Opera and People's Opera, but also in Graz. Many people came to the opera because of her virtuous and fascinating singing. The people wanted to hear her sing again and again."
- H. Rosenthal and J. Warrack, Concise Oxford Dictionary of Opera (OUP, London 1974 printing).
- Rosenthal and Warrack 1974.
- "Reply to a parliamentary question" (pdf) (in German). p. 1067. Retrieved 25 January 2013.
- H. Furch, E. A. Smolik and E. Werthan, Kammersängerin Mimi Coertse... (Vienna 2002), pp. 5-6.
- Furch, Smolik and Werthan 2002, p. 31.
- Helmuth Furch, 'Die Wiener Jahre von Kammersängerin Mimi Coertse,' ('The Viennese years of Kammersängerin Mimi Coertse'), Bulletin of Museums- und Kulturverein Kaisersteinbruch No. 41, 20-56, March 1996: also 'Mimi Coertse, die hochgeschätzte Konzert- und Liedsängerin' ('A reverence for a great Concert- and Lieder-singer'), ibid. No. 52, 33-54, December 1998.
- Helmuth Furch, Eva Hilda Smolik and Elfriede Werthan, Kammersängerin Mimi Coertse, eine Wienerin aus Südafrika (Kammersängerin Mimi Coertse, a Viennese woman from South Africa) (with a preface by Marcel Prawy), (Vienna 2002).