After completing his studies with Helmut Hucke at the Cologne Musikhochschule, Hans-Peter Westermann in 1976 became a member of the Orchestra of the Deutsche Oper Berlin,and later of the WDR Symphony Orchestra Cologne.
From 1982 onwards he opted for a freelance career and appeared with many leading ensembles, including Concentus musicus Wien, musica antiqua Köln, Cappella Coloniensis, Neue Düsseldorfer Hofmusik, das Reicha’sche Quintett, Sonatori de la Gioiosa Marca, Anima eterna Brügge.
Between 1988 and 1992 he was visiting professor of oboe at the Musikhochschule in Vienna and up to 2009 he taught at the Musikhochschule in Frankfurt. Since 1989 Hans-Peter Westermann has also devoted himself to instrument making.