He coached eight years in the German Basketball Bundesliga with BG Göttingen and Brose Bamberg and in Italy in the Lega Basket Serie A with Pallacanestro Varese.
Roijakkers won 3 championships in 3 different countries and was national team coach for the Netherlands U18 4 years in a row.
As an assistant coach Roijakkers worked together with Chris Finch for five years in Belgium with Bree B.B.C and Dexia Mons-Hainaut.
The ULEB Cup campaign included wins against Alba Berlin, Aris B.C., Lukoil Academic and BK Ventspils.
His first head coaching job came in 2011 with BC Prievidza in Slovakia, where he won the national title in the Slovakian ExtraLiga his first year.
[9] On 1 July 2020 Roijakkers signed a three-year contract[10] as the head coach of Brose Bamberg who competed in the German BBL and the Basketball Champions League.
On 12 January 2022 he replaced Adriano Vertemati as the head coach of Pallacanestro Varese in the Italian Lega Basket Serie A.
[20] On 14 June 2022 he was announced as the new coach of Belgium 2de Landelijke side Bree B.B.C, returning to old stomping grounds.
[23] He competed with the Saudi Arabia men's national team in the Asian Qualifiers for the 2023 FIBA Basketball World Cup.