Born 2 November 1948 in Minsk into a family of opera singers, Dmitri Nikolaevich Smirnov entered the Moscow Conservatoire in 1967. Here studied composition with Nikolai Sidelnikov, orchestration with Edison Denisov, and analysis with Yury Kholopov. He also studied with Webern's pupil Philip Herschkowitz. He is married to Elena Firsova, a composer.  They have children Philip (an artist and sculptor) and Alissa (a pianist and composer). 

From 1973 to 1980 he was an editor for the publisher Sovetsky Kompozitor. Since then he has pursued a career as a freelance composer. His Solo for Harp won First Prize in a competition in Maastricht (1976). Since then on his music has received an increasing number of performances. In 1989 his opera Tiriel (on a text by William Blake) was premiered at the Freiburg Festival in Germany, and its companion piece Thelwas performed at the Almeida Festival in London. That year his First Symphony (The Seasons) was performed at the Tanglewood Festival, USA. His orchestral Mozart-Variations were staged as a ballet in Pforzheim in Germany (1992). Other premieres include the oratorio A Song of Liberty (Leeds – 1993), Cello Concerto (Manchester, UK – 1996), cantata Song of Songs, (Geneva – 2001) Triple Concerto 2 (LSO, Barbican, London – 2004). Many of Smirnov's works reflect his fascination with the poetry of William Blake or express his response to Blake's drawings and paintings. 

Smirnov was one of the founders of Russia's new Association for Contemporary Music, established in Moscow in 1990. Since 1991 Smirnov, his wife, have been resident in England. Here they have shared the position of Composer-in-Residence at Cambridge University (St John's College), spent a year at Dartington (1992), and were Visiting Professors at Keele University (from 1993 to 1998). In 1998 Smirnov and his family settled in St Albans, near London. From 2003 he teaches at the Goldsmiths college of Music in London. 

Smirnov's music has been played by international conductors, including Martin Brabbins, Sir Andrew Davis, Dennis Russell Davies, Peter Eoetvoes, Lionel Friend, Oliver Knussen, Pavel Kogan, Alexander Lazarev, Reinbert de Leeuw, Jerzy Maksimiuk, Lev Markiz, Gerhard Markson, Diego Masson, Yuri Nikolajevski, Gennadi Rozhdestvenski, Gunther Schuller, Vassili Sinaiski, Neal Stulberg, Yan Pascal Tortelier, and Guillaume Tourniaire.  Recent commissions have been from the London Simphony Orchestra, L’Orchestra de la Suisse Romande, The Nieuw Sinfonietta of Amsterdam, The Netherlands Blazer Ensemble, London Sinfonietta, Brodsky Quartet, Vanbrugh Quartet,  Dante Quartet, Nash Ensemble, Fretwork, Legrand Ensemble, Leeds Festival Chorus, The Music Group of Manchester, Cheltenham, West Cork and Dartington Summer Festivals, University of Liverpool and Rodewald Concerts Society Karine Georgian and Mstislav Rostropovich. 

Smirnov's books A Geometer of Sound Crystals and  The Anatomy of Theme in Beethoven's Piano Sonatas (studia slavica musicologica, vol. 34 & 46, in English) were published by Ernst Kuhn, Berlin  (available on Ernst-Kuhn-Verlag@t-online.de) His music is available through Publishers Boosey & Hawkes (London), Hans Sikorski (Hamburg), G. Schirmer (New York), www.sibeliusmusic.com, and Meladina Press (St Albans).