A graduate of the Fryderyk Chopin Academy of Music in Warsaw in the vocal class of Professor Włodzimierz Zalewski. He has perfected his vocal art at master classes with Professor Ryszard Karczykowski and William Mateuzzi. In 1997 he made his debut in the role of Don Magnifico in Rossini's La Cenerentola (Cinderella) at the Warszawska Opera Kameralna (Warsaw Chamber Opera). The artist collaborates with: Teatr Wielki-Opera Narodowa in Warsaw, Opera Bałtycka in Gdansk, Opera Krakowska in Cracow, Teatr Wielki in Lodz and Opera Wrocławska in Wroclaw. He has made guest appearances in among others: Teatr Wielki in Poznan, Polska Opera Królewska in Warsaw, Warszawska Opera Kameralna in Warsaw, Oper Frankfurt am Main, Wuppertaler Bühnen, Lithuanian National Opera and Ballet Theatre, Theater der Stadt Koblenz, Wienerkammeroper.

His repertoire includes parts in such operas as: Le nozze di Figaro (The Marriage of Figaro), Don Giovanni, Die Zauberflöte (The Magic Flute) and Così fan tutte by Mozart; Il barbiere di Siviglia (The Barber of Seville), La Cenerentola (Cinderella), Il Turco in Italia (The Turk in Italy), L’italiana in Algiery (The Italian Girl in Algiers), La pietra del paragone and Il viaggio a Reims (The Journey to Reims) by Rossini; L’elisir d’amore (The Elixir of love), Don Pasquale and Lucrezia Borgia by G. Donietti; Halka, Hrabina (The Countess) and Verbum nobile by Moniuszko; Der Kaiser von Atlantis (The Emperor of Atlantis) by Ullmann, Der Freischütz by Weber and Lohengrin, Parsifal, Tristan and Isolde by Wagner.

He participated in numerous music festivals, such as: Rossini Opera Festival (Pesaro), Festival de Musique de Strasbourg, "Rossini in Wildbad" Belcanto Opera Festival (Germany), Euroradio/EBU Summer Music Festival (Warsaw), Festival di Musica Sacra "Anima Mundi" (Pisa), Internationalen Maifestspiele (Wiesbaden), International Moniuszko Festival, Warsaw Autumn, Wratislavia Cantans, Bydgoszcz Opera Festival, Adam Didur Festival (Sanok, Poland), International Karol Kurpiński Music Festival. He took part in the world premieres of Kurt Schwertsik's Katzelmacher (Wuppertal, 2003) and Zygmunt Krauze's Yvonne, The Princess of Burgundy (Paris, 2004).

Dariusz Machej has performed under the baton of such conductors as: Bassem Akiki, Benjamin Bayl, Adam Banaszak, Grzegorz Berniak, Mirosław Jacek Błaszczyk, Jacek Boniecki, Łukasz Borowicz, Roland Böer, Martin Braun, Tomasz Bugaj, Kai Bumann, Massimiliano Caldi, Gabriel Chmura, Will Crutchfield, Johannes Debus, Michał Dworzyński, José Maria Florêncio, Patrick Fournillier, Florian Frannek, Zbigniew Graca, Hilary Griffiths, Walter Gugerbauer, Friedrich Haider, George Hanson, Chikara Imamura, Tadeusz Karolak, Jacek Kaspszyk, Michał Klauza, Stefan Klieme, Rafał Kłoczko, Andrzej Knap, Paweł Kotla, Tadeusz Kozłowski, Warcisław Kunc, Alexander Liebreich, Jean Claude Malgoire, Alessandro de Marchi, Carlo Montanaro, Marcin Nałęcz-Niesiołowski, Grzegorz Nowak, Wojciech Rajski, Carlo Rizzi, Wojciech Rodek, Dawid Runtz, Tadeusz Serafin, Ruben Silva, Stefan Soltesz, Karen Schulze-Koops, Simon Standage, Andrzej Straszyński, Tadeusz Strugała, Piotr Sułkowski, Tomasz Tokarczyk, Dirk Vermeulen, Evgeny Volynski, Maciej Wieloch, Tadeusz Wojciechowski, Sławek A. Wróblewski, Antoni Wit, Andriy Yurkevych, Jan Miłosz Zarzycki and Alberto Zedda.

He has worked with directors such as: Laco Adamik, Henryk Baranowski, Andrzej Bubień, Eva Buchmann, Grzegorz Chrapkiewicz, Willy Decker, Kazimierz Dejmek, Beata Redo-Dobber, Achim Freyer, Agnieszka Glińska, Jerzy Gruza, André Heller-Lopes, Grzegorz Jarzyna, Janusz Józefowicz, Natalia Korczakowska, Constanze Kreusch, Gerd Leo Kuck, Giorgio Madia, Peter Mussbach, Włodzimierz Nurkowski, Ryszard Peryt, Pier Luigi Pizzi, José Carlos Plaza, Niels-Peter Rudolph, Emilio Sagi, Maria Sartova, Volker Schmalöer, Torsten Schröder, Jitka Stokalska, Andrzej Strzelecki, Jerzy Stuhr, Paweł Szkotak, Cezary Tomaszewski, Mariusz Treliński, Krzysztof Warlikowski, Keith Warner, Johannes Weigand, Marek Weiss, Barbara Wysocka and Michał Znaniecki.

The artist also performs in oratorio and lieder repertoire. He has sung in many prestigious concert halls in Poland and abroad (Switzerland, Germany, Spain, France, Lebanon, China, Japan). He has taken part in numerous radio and television broadcasts (RAI, Südwestrundfunk, Polish Radio and Polish TV, Polsat). He has made many recordings for phonographic companies (Naxos, ROF, Bongiovanni, DUX, Radio Phonographic Agency) and the archives of the Polish Radio. His recording of Karol Szymanowski's Hagith with received the Fryderyk 2020 Award in the Classical Music category: Album of the Year Oratorio and Opera Music.