The Belgian played from the start as the Giallorossi beat Sampdoria 1-0 thanks to Vasilis Torosidis' early strike to book a Coppa Italia quarter-final date with Juventus
The Belgian, who joined as part of a co-ownership deal with Cagliari earlier this week, started for the Giallorossi in Thursday's victory, which came about thanks to an early goal from Vasilis Torosidis.
Rudi Garcia's men will now meet Juventus in a tantalising quarter-final encounter after the Serie A champions saw off Avellino in their own last-16 meeting.
Roma, desperate to make amends for their 3-0 defeat to Juventus in their last outing, were on the attack from the off and opened the scoring with just six minutes on the clock. Vincenzo Fiorillo did superbly to deny Mattia Destro following Dodo's cross, but Torosidis was on hand to turn home the follow-up.
Nainggolan himself came close to a memorable debut goal, but Fiorillo stuck out a leg to deny his effort from the edge of the area.
Destro missed a great chance to seal the win late on but ultimately Garcia's side were good value for their win and will now prepare to meet Antonio Conte's side on January 21.