When Allan Kuhn resigned on 15 April 2011, Riddersholm was promoted to the position as head coach.[4] Riddersholm led the club to its first Danish championship in the 2014-15 Danish Superliga, but shortly after he resigned as manager of the club.[5]
On 6 December 2015 he was named successor of Morten Wieghorst as manager of AGF.[6] He was sacked in September 2017.
In October 2018 he was named new director of sports of Vendsyssel FF.[7]
On 19 December 2018 it was announced that Riddersholm would become new manager of SønderjyskE in the Danish Superliga starting on 1 February 2019.[8]
On 26 May 2021, it was announced that he would not be the manager of SønderjyskE going forward as the club's owners had decided to make changes in the club's management.
On 8 August 2022 he was hired as new manager of Swedish Allsvenskan club IFK Norrköping succeeding the sacked Rikard Norling.[10] Riddersholm left by mutual consent on 13 November 2023.[11]