Dirk Keijzer studied Composition/Arranging Jazz at the Conservatorium van Amsterdam, graduating in 1985. He arranged thousands of works for radio, TV, CD in the genres of cabaret, pop music, musical and jazz. He worked for musicians such as Cor Bakker, Tonny Eyk, Ruud Mulder, Lee Towers, Edwin Schimscheimer, Harry van Hoof and Maurice Luttikhuis and orchestras and bands including the Metropole Orchestra, the orchestra of the Royal Netherlands Air Force, the Salvation Army brass band, the orchestra of the Royal Netherlands Navy and numerous amateur orchestras and choirs.

He also composed works for Cor Bakker en Tonny Eyk. Together with Cor Bakker he composed Zomaar een dag for singer Willeke Alberti, which was runner-up at the 1993 National Song Festival. Other works include six pieces for classical symphony orchestra for the Holiday on Ice show Romanza. He also released a solo cd with original compositions.

Dirk has been a teacher at the Conservatorium van Amsterdam since 1981, teachting ear training, arranging and harmony at the piano.