Two years later, Schiller made his debut in the IMSA SportsCar Championship at the 2019 24 Hours of Daytona, driving for P1 Motorsports. After retiring, the entry finished 19th in class. Two seasons later, Schiller returned to the series, competing with DragonSpeed in the LMP2 class. The team finished on the podium in class, four laps behind the second-placed Tower Motorsport by Starworks entry.