Frontzeck started as assistant coach of Borussia Mönchengladbach from 2000 to 2003 and for Hannover 96 from 2004 to 2005. He was manager of Alemannia Aachen from 2006 until the end of the season 2006–07 when he resigned due to the club's relegation. In January 2008, he was named manager of Arminia Bielefeld and took over for interim manager Detlev Dammeier after the winter break. Eventually, it was announced that his contract was extended until 2010 but on 17 May 2009, Frontzeck was fired.
On 3 June 2009, Borussia Mönchengladbach announced Frontzeck's return to the team as new head coach. He signed a two-year-contract until 30 June 2011. Following the loss against FC St. Pauli on 13 February 2011 Frontzeck was released as head coach by the club management of Borussia Mönchengladbach.