After the resignation of Adelaide United manager
John Kosmina on 28 January 2013, Valkanis was appointed caretaker manager of Adelaide United for the remainder of the A-League season. Under Valkanis, Adelaide United managed to finish the A-League season in fourth place, therefore qualifying for the A-League finals. However, they were eliminated in the first round by
Brisbane Roar. In May 2016, Valkanis left Adelaide United. In June 2016, Valkanis joined
Melbourne City as the senior assistant coach to
John van 't Schip. On 3 January 2017, after the resignation of Melbourne City manager
John van't Schip, Valkanis was appointed manager of the club for the remainder of the season. On May 9, 2018, Dutch Eredivisie club
PEC Zwolle announced Valkanis had been appointed assistant to manager
John van't Schip on a one-year deal with a one-year option. On November 1, 2023,
Ajax announced Valkanis had been appointed assistant to manager
John van't Schip on a one-year deal with a one-year option. On July 8, 2024,
Adana Demirspor announced Valkanis had been appointed as manager on a one-year deal with a one-year option. ==Personal life==