Born in Göttingen, Hiekel first studied musicology, art history and history at the universities of Cologne and Bonn before he completed his double bass studies at the Musikhochschule Köln.
He worked for many years as editor and publisher at the Breitkopf & Härtel music publishing house and as author for various ARD institutions and newspapers/magazines (including the Frankfurter Allgemeine Zeitung and Opernwelt).
From 2003 he was assistant professor for 20th century music at the Hochschule für Musik Carl Maria von Weber Dresden.
Since 2008 he is lecturer for music aesthetics and musicology at the Zurich University of the Arts.
Since 2008 he is head of the mediation project KlangNetz Dresden [de], since 2012 board member of KlangNetz Dresden e. V. 2004-2019 he was board member of the Darmstadt Institute for New Music and Music Education (INMM), which he took over in 2013.